1,407 research outputs found

    Methodology for the creation of synthetic data for quality management and predictive maintenance in the field of hydroforming (IHU)

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    Companies are increasingly challenged by the impending loss of knowledge due to demographic change and employee loss. In times of advancing digitalization, it is important to make large datasets accessible and usable, aiming at increasing resource efficiency within the company on the one hand and being able to offer customers additional services on the other. Given the background of implementing efficient quality management and predictive maintenance with the same system, technological key figures and process control must first be determined. In the field of intelligent maintenance, however, it is not always possible to record error states of physical systems in series operation as a data set. Deliberately allowing faults to occur under real production conditions could lead to fatal failures or even the destruction of the system. The targeted generation of faults under highly controlled conditions can also be timeconsuming, cost-intensive, or even impractical

    Advanced information processing system: Fault injection study and results

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    The objective of the AIPS program is to achieve a validated fault tolerant distributed computer system. The goals of the AIPS fault injection study were: (1) to present the fault injection study components addressing the AIPS validation objective; (2) to obtain feedback for fault removal from the design implementation; (3) to obtain statistical data regarding fault detection, isolation, and reconfiguration responses; and (4) to obtain data regarding the effects of faults on system performance. The parameters are described that must be varied to create a comprehensive set of fault injection tests, the subset of test cases selected, the test case measurements, and the test case execution. Both pin level hardware faults using a hardware fault injector and software injected memory mutations were used to test the system. An overview is provided of the hardware fault injector and the associated software used to carry out the experiments. Detailed specifications are given of fault and test results for the I/O Network and the AIPS Fault Tolerant Processor, respectively. The results are summarized and conclusions are given

    Occupation time statistics of the random acceleration model

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    The random acceleration model is one of the simplest non-Markovian stochastic systems and has been widely studied in connection with applications in physics and mathematics. However, the occupation time and related properties are non-trivial and not yet completely understood. In this paper we consider the occupation time T+T_+ of the one-dimensional random acceleration model on the positive half-axis. We calculate the first two moments of T+T_+ analytically and also study the statistics of T+T_+ with Monte Carlo simulations. One goal of our work was to ascertain whether the occupation time T+T_+ and the time TmT_m at which the maximum of the process is attained are statistically equivalent. For regular Brownian motion the distributions of T+T_+ and TmT_m coincide and are given by L\'evy's arcsine law. We show that for randomly accelerated motion the distributions of T+T_+ and TmT_m are quite similar but not identical. This conclusion follows from the exact results for the moments of the distributions and is also consistent with our Monte Carlo simulations.Comment: 10 pages, 4 figure

    Programming Service Oriented Agents

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    This paper introduces a programming language for service-oriented agents. JADL++ combines the ease of use of scripting-languages with a state-of-the-art service oriented approach which allows the seamless integration of web-services. Furthermore, the language includes OWL-based ontologies for semantic descriptions of data and services, thus allowing agents to make intelligent decisions about service calls

    Microplastics profile along the Rhine River

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    Microplastics result from fragmentation of plastic debris or are released to the environment as pre-production pellets or components of consumer and industrial products. In the oceans, they contribute to the ‘great garbage patches’. They are ingested by many organisms, from protozoa to baleen whales, and pose a threat to the aquatic fauna. Although as much as 80% of marine debris originates from land, little attention was given to the role of rivers as debris pathways to the sea. Worldwide, not a single great river has yet been studied for the surface microplastics load over its length. We report the abundance and composition of microplastics at the surface of the Rhine, one of the largest European rivers. Measurements were made at 11 locations over a stretch of 820 km. Microplastics were found in all samples, with 892,777 particles km −2 on average. In the Rhine-Ruhr metropolitan area, a peak concentration of 3.9 million particles km −2 was measured. Microplastics concentrations were diverse along and across the river, reflecting various sources and sinks such as waste water treatment plants, tributaries and weirs. Measures should be implemented to avoid and reduce the pollution with anthropogenic litter in aquatic ecosystems

    Forestland controlled by schools of forestry: Characteristics and management

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    Most forestry schools control forestland. Traditionally, the school forest has served as a laboratory for field instruction and research. This article reports on a 1985-86 survey of the 1 candidate and 46 accredited forestry schools in the United States on the ownership, objectives, and management of school forests. The survey\u27s purpose was to determine the extent and distribution of forestland ownership by forestry schools. The survey addressed how the forestry schools gained control of the land; the objectives of forest management, and how important the school forest was to the teaching, research, and service functions of the university. The importance of revenue production and the allocation of school forest revenue was also established

    Variations of Steroid Hormone Metabolites in Serum and Urine in Polycystic Ovary Syndrome after Nafarelin Stimulation: Evidence for an Altered Corticoid Excretion.

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    To evaluate the clinical relevance of testing pituitary-ovarian responses in patients suffering from polycystic ovary syndrome (PCOS) with the GnRH agonist nafarelin, a 1.2-mg dose of nafarelin was given intranasally to 19 women with PCOS and 15 healthy premenopausal women. The subsequent analysis of steroids in both serum and urine during the test was carried out at several time points for up to 24 h. Serum levels of 17 alpha-hydroxyprogesterone were elevated at all time points of the test in PCOS patients vs. controls [at baseline, 3.5 +/- 0.2 vs. 1.8 +/- 0.1 nmol/L (P < 0.001); at 24 h, 9.9 +/- 0.9 vs. 4.9 +/- 0.3 nmol/L (P < 0.001)]. Basal levels of androstenedione were higher in the patient group, but there was no significant change during the test in either group. Serum testosterone levels were also found to differ in PCOS patients compared with the control values at baseline (2.2 +/- 0.2 vs. 1.5 +/- 0.1 nmol/L; P < 0.05) and after nafarelin treatment (at 24 h, 3.2 +/- 0.4 vs. 1.8 +/- 0.2 nmol/L; P < 0.05). Serum estradiol levels rose significantly in both groups during the test; the posttest levels were significantly higher in PCOS than in controls. The PCOS patients displayed a significant increase in androgen and gestagen metabolites as well as in glucocorticoid metabolites excreted in the urine during the 24 h. In the control subjects, except for 17 alpha-hydroxypregnanolone, which rose significantly, none of the urinary steroids investigated showed relevant changes during the nafarelin test. The posttest excretion of allo-tetrahydrocortisol (1.4 +/- 0.2 vs. 0.3 +/- 0.1 mumol/g creatinine; P < 0.001) and the increase in 17 alpha-hydroxypregnanolone excretion (1.4 +/- 0.2 vs. 0.3 +/- 0.1 mumol/g creatinine; P < 0.001) were distinctly higher in PCOS patients than in the controls; the diagnostic sensitivity of the combination of both parameters was 89% at a 93% specificity. Thus, measurements of 17 alpha-hydroxyprogesterone levels in serum and of urinary allo-tetrahydrocortisol and 17 alpha-hydroxypregnanolone after nafarelin treatment make this stimulation test a valuable diagnostic tool for identifying PCOS patients. The significant changes in the excretion of urinary androgen and gestagen metabolites, unmasked by GnRH agonist stimulation, suggest a functional alteration of the pituitary-ovarian axis. The reason for the increased excretion of glucocorticoid metabolites after nafarelin stimulation remains to be clarified

    The Severity of Injury and the Extent of Hemorrhagic Shock Predict the Incidence of Infectious Complications in Trauma Patients

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    Abstract : Background: : Trauma patients are at high risk of developing systemic inflammatory response syndrome (SIRS) and infections. The aim of this study was to evaluate the influence of the severity of injury and the extent of hemorrhagic shock at admission on the incidence of SIRS, infection and septic complications. Methods: : A total of 972 patients who had an injury severity score (ISS) of ≄ 17, survived more than 72 h, and were admitted to a level I trauma center within 24 h after trauma were included in this retrospective analysis. SIRS, sepsis and infection rates were measured in patientswith different severities of injury as assessed by ISS, or with various degrees of hemorrhagic shock according to ATLSÂź guidelines, andwere compared using both uni- and multivariate analysis. Results: : Infection rates and septic complications increase significantly (p < 0.001) with higher ISS. Severe hemorrhagic shock on admission is associated with a higher rate of infection (72.8%) and septic complications (43.2%) compared to mild hemorrhagic shock (43.4%, p < 0.001 and 21.7%, p < 0.001, respectively). Conclusion: : The severity of injury and the severity of hemorrhagic shock are risk factors for infectious and septic complications. Early diagnostic and adequate therapeutic work up with planned early "second look" interventions in such high-risk patients may help to reduce these common posttraumatic complication

    Patch-clamping mit Mikroöffnungen in Polyimide-Folien

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    Die Patchclamp-Technik ist die aussagekrĂ€ftigste Methode zur Untersuchung der Funktion und Regulation von IonenkanĂ€len. Sie basiert auf der Bildung eines engen Kontaktes zwischen der Spitze einer Glasspipette und der Membran einer Zelle, an die die Pipette herangefĂŒhrt wird. Aus dem engen Kontakt resultiert ein elektrischer Widerstand im Gigaohm-Bereich zwischen der Elektrolytlösung im Innern der Pipette und der die Zelle und Pipette umgebenden Elektrolytlösung. Trotz der weitverbreiteten Verwendung dieser Methode ist die wahre Natur dieses Kontaktes und der resultierenden hochohmigen „Seal“-Bildung noch immer nicht im Detail verstanden. Zudem ist die Patchclamp-Methode zeitaufwendig und erfordert erfahrene Anwender sowie gutausgerĂŒstete Setups. Im Moment ist noch keine Vorrichtung beschrieben, die diesen “Cell-by-cell”-Assay vollautomatisch durchfĂŒhrt. Dies ist jedoch die Voraussetzung fĂŒr Automatisierung, Miniaturisierung und Parallelisierung, um mit dieser Methode Hochdurchsatz-Untersuchungen von pharmazeutischen Substanzen durchfĂŒhren zu können. Mehrere Gruppen berichten ĂŒber einen Ansatz, der die Glasspipette durch eine mikromechanisch gefertigte Siliziumstruktur ersetzen soll. Sie verwenden ein dĂŒnnes Diaphragma, in das ein mikroskopisch kleines Loch (Durchmesser im Nano- und Mikrometer-Bereich) eingebracht ist. Darauf werden Lipidvesikel aufgebracht, die per AdhĂ€sion die Umgebung der Mikroöffnung hochohmig abdichten. Mit dieser Methode lassen sich Einzelkanalströme messen
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