Butterfly-effect for massively separated flows

2014 ◽  
Vol 31 (4) ◽  
pp. 742-757 ◽  
Author(s):  
Rainald Lohner ◽  
Dominic Britto ◽  
Alexander Michailski ◽  
Eberhard Haug
Keyword(s):  
Large Scale ◽  
Separated Flows ◽  
Wind Engineering ◽  
Content Type ◽  
Massively Separated Flows ◽  
Time Requirements ◽  
The Mean ◽  
Butterfly Effect ◽  
First Time ◽  
Inflow Conditions

Purpose – During a routine benchmarking and scalability study of CFD codes for typical large-scale wind engineering runs, it was observed that the resulting loads for buildings varied considerably with the number of parallel processors employed. The differences remained very small at the beginning of a typical run, and then grew progressively to a state of total dissimilitude. A “butterfly-effect” for such flows was suspected and later confirmed. The paper aims to discuss these issues. Design/methodology/approach – A series of numerical experiments was conducted for massively separated flows. The same geometry – a cube in front of an umbrella – was used to obtain the flowfields using different grids, different numbers of domains/processors, slightly different inflow conditions and different codes. Findings – In all of these cases the differences remained very small at the beginning of a typical run, they then grew progressively to a state of total dissimilitude. While the mean and maximum loads remained similar, the actual (deterministic) instantiations were completely different. The authors therefore suspect that for flows of this kind a “butterfly effect” is present, whereby even very small (roundoff) errors can have a pronounced effect on the actual deterministic instantiation of a flowfield. Research limitations/implications – This implies that for flows of this kind the CFD runs have to be carried out to much larger times than formerly expected (and done) in order to obtain statistically relevant ensembles. Practical implications – For practical calculations this implies running to much larger times in order to reach statistically relevant ensembles, with the associated much higher CPU time requirements. Originality/value – This is the first time such a finding has been reported in the numerical wind engineering context.

Conflict resolution practice in public procurement: evidence from Russia

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yuliya Rodionova
Keyword(s):  
Conflict Resolution ◽  
Large Scale ◽  
Public Procurement ◽  
Content Type ◽  
Conflict Situations ◽  
Judicial Proceedings ◽  
Survey Results ◽  
Conflict Handling ◽  
Informal Relations ◽  
First Time

Purpose This paper aims to analyze conflict resolution practice in public procurement. The specific feature of this sphere is the presence of the state and the resulting differences in assessing the chances of protecting one’s interests in court, as well as the effectiveness of judicial conflict resolution mechanisms. Design/methodology/approach This paper is based on the findings of a large-scale survey of suppliers conducted in 2017. To identify the characteristics of suppliers that use different conflict resolution mechanisms, probit-models were evaluated. For robustness check, combined mechanisms for resolving conflict situations were also considered and multi-nomial logistic regression was used. Findings The survey results showed that the majority of suppliers prefer to resolve conflicts in public procurement using an out-of-court negotiation with procurers while only 31% of respondents resort to judicial proceedings. At the same time, suppliers potentially involved in informal relations with procurers, are less likely to go to court and less often use negotiations. Practical implications The results of the study can be used as a justification for the development of a regulatory and organizational framework for the use of negotiations, mediation, arbitration and other alternate methods of conflict resolution in public procurement. Originality/value This paper makes an important contribution to the conflict-handling strategies of businesses and government by presenting for the first time a quantitative assessment of the prevalence of mechanisms for resolving conflicts in public procurement and factors influencing the choice of a conflict resolution mechanism.

Environment and technology dominate the WEF agenda

2017 ◽  
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
The United States ◽  
Extreme Weather Events ◽  
Content Type ◽  
Mitigation And Adaptation ◽  
The People ◽  
Impact Risk ◽  
Trade Deals ◽  
First Time

Significance For the first time in the eleven-year history of the survey, no economic risk makes the list of the top five most likely or biggest impact risks. In contrast, large-scale terrorist attacks make the top five most likely risks for the first time and weapons of mass destruction are cited as the highest impact risk. All five environment-related risks are ranked among the top ten highest impact risks for the first time -- four in the top five: extreme weather events; water crises; major natural disasters; and failure of climate change mitigation and adaptation. The survey cites strengthening global cooperation systems as a top five challenge, and says these environmental risks will be exacerbated if cooperation diminishes. Impacts Nearly a third of respondents think that increasing polarisation will be an underlying trend over the next ten years. More must be done to include the people left behind by technological change -- more than 4 billion lack internet access. The United States may withdraw from the Paris climate change agreement, and a number of free trade deals are at risk.

scholarly journals Right-first-time dyeing: a design of experiments approach for the optimisation of dyeing-processes using hard water

2019 ◽  
Vol 48 (5) ◽  
pp. 449-455
Author(s):  
Saira Faisal ◽  
Aurelio Tronci ◽  
Muhammad Ali ◽  
Erum Bashir ◽  
Long Lin
Keyword(s):  
Predictive Models ◽  
Textile Industry ◽  
Large Scale ◽  
Mineral Content ◽  
Water Hardness ◽  
Hard Water ◽  
Coefficient Of Determination ◽  
Content Type ◽  
Independent Variables ◽  
First Time

Purpose The purpose of this study was to optimise the dyeing conditions to achieve right-first-time dyeing in hard water. Owing to the persistent water scarcity for more than two decades now, the textile industry in Pakistan is forced to rely on high-mineral-content ground water for use in textile wet processing. Furthermore, the limited amount of municipal water that is at the disposal of the textile industry is also high in mineral content. Thus, on the large scale, water hardness has become an acute problem for the textile processor. In particular, in the dyeing process, water hardness is known to have crucial effects. However, to-date, no systematic study has been conducted on this aspect of textile dyeing. Design/methodology/approach In this study, 32 full factorial design was used to optimise the dyeing conditions to achieve right-first-time dyeing in hard water. Thus, cotton fabric was dyed with Red Reactive dye (of dyebath concentration at 5, 10 and 15 g/L) in prepared hard water (of hardness at 10, 40 and 70°dH), respectively. Analysis of variance, coefficient of determination (R2) and p-values for the models were used to evaluate the adequacy of the predictive models. The surface plots of the effects were studied to further examine the interactions of two independent variables. Derringer’s desirability function was used to determine the optimum levels of each variable. Findings Three levels for both independent variables generate second-order polynomial models to predict the colour strength, lightness, red/green, yellow/blue and total colour difference values of dyed cotton. The obtained predictive models point out the considerable influence of both water hardness and dye concentration on right-first-time dyeing. Originality/value Such a finding enabled the dye-mill to produce the correct shade at water hardness of 10°dH and 15 g/L dye concentration, without the need for corrective reprocessing.

scholarly journals Generalizing Cloud Overlap Treatment to Include Solar Zenith Angle Effects on Cloud Geometry

2007 ◽  
Vol 64 (6) ◽  
pp. 2116-2125 ◽  
Author(s):  
Adrian M. Tompkins ◽  
Francesca Di Giuseppe
Keyword(s):  
Zenith Angle ◽  
Large Scale ◽  
Solar Zenith Angle ◽  
Forecast Model ◽  
Simple Extension ◽  
Scale Models ◽  
Field Geometry ◽  
The Mean ◽  
The Impact ◽  
First Time

Shortwave radiative transfer depends on the cloud field geometry as viewed from the direction of the sun. To date, the radiation schemes of large-scale models only consider a zenith view of the cloud field, and the apparent change in the cloud geometry with decreasing solar zenith angle is neglected. A simple extension to an existing cloud overlap scheme is suggested to account for this for the first time. It is based on the assumption that at low sun angles, the overlap between cloud elements is random for an unscattered photon. Using cloud scenes derived from radar retrievals at two European sites, it is shown that the increase of the apparent cloud cover with a descending sun is reproduced very well with the new scheme. Associated with this, there is a marked reduction in the mean radiative biases averaged across all solar zenith angles with respect to benchmark calculations. The scheme is implemented into the ECMWF global forecast model using imposed sea surface temperatures, and while the impact on the radiative statistics is significant, the feedback on the large-scale dynamics is minimal.

scholarly journals Immunoprofiling of the Tryptophan-Rich Antigen Family in Plasmodium vivax

2015 ◽  
Vol 83 (8) ◽  
pp. 3083-3095 ◽  
Author(s):  
Bo Wang ◽  
Feng Lu ◽  
Yang Cheng ◽  
Jun-Hu Chen ◽  
Hye-Yoon Jeon ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Protein Microarray ◽  
Expression System ◽  
Membrane Structures ◽  
Igg Antibody ◽  
Content Type ◽  
Seropositive Rate ◽  
A Cell ◽  
The Mean ◽  
First Time

Tryptophan-rich antigens (TRAgs) are an antigen family that has been identified in human and rodent malaria parasites. TRAgs have been proposed as candidate antigens for potential vaccines. ThePlasmodium vivaxTRAg (PvTRAg) family includes 36 members. Each PvTRAg contains a tryptophan-rich (TR) domain in the C-terminal region. In this study, we recombinantly expressed all 36 PvTRAgs using a cell-free expression system, and, for the first time, profiled the IgG antibody responses against all PvTRAgs in the sera from 96 vivax malaria patients and 40 healthy individuals using protein microarray technology. The mean seropositive rate for all PvTRAgs was 60.3%. Among them, nine PvTRAgs were newly identified in this study and showed a seropositive rate of >50%. Five of them, PvTRAg_13, PvTRAg_15, PvTRAg_16, PvTRAg_26, and PvTRAg_29, produced higher levels of IgG antibody, even in low-endemicity countries. In addition, the results of an immunofluorescence analysis suggest that PvTRAgs are, at least in part, associated with caveola-vesicle complexes, a unique structure ofP. vivax-infected erythrocytes. The mechanism of formation and the function of these abundant membrane structures are not known. Further investigation aimed at determining the functions of these proteins would lead to a better understanding of the blood-stage biology ofP. vivax.

scholarly journals The Aspergillus nidulansnucAEndoGHomologue Is Not Involved in Cell Death

2010 ◽  
Vol 10 (2) ◽  
pp. 276-283 ◽  
Author(s):  
Bárbara de Castro Pimentel Figueiredo ◽  
Patrícia Alves de Castro ◽  
Taísa Magnani Dinamarco ◽  
Maria Helena S. Goldman ◽  
Gustavo Henrique Goldman
Keyword(s):  
Cell Death ◽  
Aspergillus Nidulans ◽  
Dna Fragmentation ◽  
Filamentous Fungi ◽  
Large Scale ◽  
Apoptosis Induction ◽  
Content Type ◽  
Endonuclease G ◽  
First Time

ABSTRACTUpon apoptosis induction, translocation of mammalian mitochondrial endonuclease G (EndoG) to the nucleus coincides with large-scale DNA fragmentation. Here, we describe for the first time a homologue of EndoG in filamentous fungi by investigating if theAspergillus nidulanshomologue of the EndoG gene, namednucAEndoG, is being activated during farnesol-induced cell death. Our results suggest that NucA is not involved in cell death, but it plays a role in the DNA-damaging response inA. nidulans.

An efficient local search for large-scale set-union knapsack problem

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yupeng Zhou ◽  
Mengyu Zhao ◽  
Mingjie Fan ◽  
Yiyuan Wang ◽  
Jianan Wang
Keyword(s):  
Knapsack Problem ◽  
Design Methodology ◽  
Large Scale ◽  
Optimization Problem ◽  
Mean Value ◽  
Convergence Time ◽  
Content Type ◽  
Statistical Experiments ◽  
Scale Optimization ◽  
First Time

PurposeThe set-union knapsack problem is one of the most significant generalizations of the Non-deterministic Polynomial (NP)-hard 0-1 knapsack problem in combinatorial optimization, which has rich application scenarios. Although some researchers performed effective algorithms on normal-sized instances, the authors found these methods deteriorated rapidly as the scale became larger. Therefore, the authors design an efficient yet effective algorithm to solve this large-scale optimization problem, making it applicable to real-world cases under the era of big data.Design/methodology/approachThe authors develop three targeted strategies and adjust them into the adaptive tabu search framework. Specifically, the dynamic item scoring tries to select proper items into the knapsack dynamically to enhance the intensification, while the age-guided perturbation places more emphasis on the diversification of the algorithm. The lightweight neighborhood updating simplifies the neighborhood operators to reduce the algorithm complexity distinctly as well as maintains potential solutions. The authors conduct comparative experiments against currently best solvers to show the performance of the proposed algorithm.FindingsStatistical experiments show that the proposed algorithm can find 18 out of 24 better solutions than other algorithms. For the remaining six instances on which the competitor also achieves the same solutions, ours performs more stably due to its narrow gap between best and mean value. Besides, the convergence time is also verified efficiency against other algorithms.Originality/valueThe authors present the first implementation of heuristic algorithm for solving large-scale set-union knapsack problem and achieve the best results. Also, the authors provide the benchmarks on the website for the first time.

Neurosurgical workforce trends in the United States

2005 ◽  
Vol 102 (2) ◽  
pp. 202-208 ◽  
Author(s):  
Oren N. Gottfried ◽  
Richard L. Rovit ◽  
A. John Popp ◽  
Kristin L. Kraus ◽  
Arlene Stolper Simon ◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Content Type ◽  
The Past ◽  
Time Period ◽  
The Us ◽  
The Mean ◽  
First Time ◽  
Second Period ◽  
Fine Print

Object. The purpose of this study was to evaluate the US neurosurgery workforce by reviewing journal recruitment advertisements published during the past 10 years. Methods. The number of available academic and private neurosurgical staff positions was determined based on recruitment advertisements in the Journal of Neurosurgery and Neurosurgery for the 10-year period from 1994 to 2003. Advertisements were evaluated for practice venue, subspecialization, and location. The numbers of active neurosurgeons and graduating residents also were reviewed. The number of advertised neurosurgical positions increased from 141.6 ± 38.2 per year from 1994 through 1998 to 282.4 ± 13.6 per year from 1999 through 2003 (mean ± standard deviation, p < 0.05). The mean number of academic positions increased from 50.6 ± 11.1 to 95 ± 17.5 (p <0.05), and the mean number of private positions rose from 91 ± 30.4 to 187.4 ± 6.8 (p <0.05). Subspecialty positions represented a mean of only 15.6 ± 5% per year during the first time period and 18.8 ± 3% per year in the second period (p = 0.22), and therefore the majority of positions advertised continued to be those for generalists. The number of practicing neurosurgeons declined after 1998, and by 2002 it was less than it had been in 1991. The numbers of incoming and matriculating residents during the study period were static. Conclusions. The number of recruitment advertisements for neurosurgeons during the last 5 years has increased significantly, concomitant with a severe decline in the number of active neurosurgeons and a static supply of residents.

scholarly journals Helicobacter pylori-Related Metabolic Parameters and Premalignant Gastric Mucosa Histological Lesions in Swiss Bariatric Patients

2021 ◽  
Vol 9 (7) ◽  
pp. 1361
Author(s):  
Michael Doulberis ◽  
Noah Thierry Pierre ◽  
Giulia Manzini ◽  
Apostolis Papaefthymiou ◽  
Jannis Kountouras ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Risk Factor ◽  
Gastric Mucosa ◽  
Arterial Hypertension ◽  
Intestinal Metaplasia ◽  
Large Scale ◽  
Statistical Significance ◽  
Bariatric Patients ◽  
The Mean ◽  
First Time

Obesity, as a major risk factor of metabolic syndrome (MetS), represents a pandemic, especially in Western societies, and is considered a risk factor for malignancies. Helicobacter pylori (Hp), is a definite carcinogen with global distribution. We aimed to investigate, for the first time in Switzerland, the main gastric mucosa premalignant histological lesions of bariatric patients in correlation with MetS components and Hp Infection (Hp-I). By reviewing retrospectively 94304 patient cases, a total of 116 eligible patients having undergone bariatric surgery were identified. The mean patient age was 48.66 years. Hp(+) patients were 24% (28/116). Presence of gastric mucosa atrophy was documented in 8/28 Hp(+) patients (29%) and (2/88) Hp(−) ones (2%) (p = 0.006). Gastric mucosa intestinal metaplasia was observed in 14/28 (50%) Hp(+) patients versus 3/88 (3.4%) of Hp(-) group (p < 0.0001). Hp(+) patients exhibited statistically higher arterial hypertension (p = 0.033). The homeostatic model of assessment insulin resistance was also statistically significantly higher for the Hp(+) group (p < 0.001). In a multivariate analysis, including arterial hypertension, gastric mucosa atrophy, and intestinal metaplasia as variables, statistical significance remained only for intestinal metaplasia (p = 0.001). In conclusion, Hp-I is associated with premalignant gastric mucosa histologic lesions and MetS components, including arterial hypertension and IR. Further large-scale prospective studies are required to confirm these findings.

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