A novel double-hybrid learning method for modal frequency-based damage assessment of bridge structures under different environmental variation patterns

Monitoring of modal frequencies under an unsupervised learning framework is a practical strategy for damage assessment of civil structures, especially bridges. However, the key challenge is related to high sensitivity of modal frequencies to environmental and/or operational changes that may lead to economic and safety losses. The other challenge pertains to different environmental and/or operational variation patterns in modal frequencies due to differences in structural types, materials, and applications, measurement periods in terms of short and/or long monitoring programs, geographical locations of structures, weather conditions, and influences of single or multiple environmental and/or operational factors, which may cause barriers to employing stateof-the-art unsupervised learning approaches. To cope with these issues, this paper proposes a novel double-hybrid learning technique in an unsupervised manner. It contains two stages of data partitioning and anomaly detection, both of which comprise two hybrid algorithms. For the first stage, an improved hybrid clustering method based on a coupling of shared nearest neighbor searching and density peaks clustering is proposed to prepare local information for anomaly detection with the focus on mitigating environmental and/or operational effects. For the second stage, this paper proposes an innovative non-parametric hybrid anomaly detector based on local outlier factor. In both stages, the number of nearest neighbors is the key hyperparameter that is automatically determined by leveraging a self-adaptive neighbor searching algorithm. Modal frequencies of two full-scale bridges are utilized to validate the proposed technique with several comparisons. Results indicate that this technique is able to successfully eliminate different environmental and/or operational variations and correctly detect damage

Relation between parvovirus B19 infection and fetal mortality and spontaneous abortion

Background: Infection with parvovirus B19 may cause fetal losses including spontaneous abortion, intrauterine fetal death and non-immune hydrops fetalis. The aim of this study is to determine the frequency of parvovirus B19 in formalin fixed placental tissues in lost fetuses using real-time PCR method. Methods: In this cross-sectional study, 100 formalin fixed placental tissues with unknown cause of fetal death were determined using real-time PCR method after DNA extraction. Results: Six out of 100 cases (6) were positive for parvovirus B19 using real-time PCR. Gestational age of all positive cases was less than 20 weeks with a mean of 12.3 weeks. Three cases have a history of abortion and all of positive cases were collected in spring. Mean age of positive cases were 28 years. Conclusion: Parvovirus B19 during pregnancy can infect red precursor cells and induces apoptosis or lyses these cells that resulting in anemia and congestive heart failure leading to fetal death. Management of parvovirus B19 infection in pregnant women is important because immediate diagnosis and transfusion in hydropsic fetuses can decrease the risk of fetal death

Recognition and identification analysis of the features of the epistemology of the MOOC (Massive and Courses)

Background and Objectives: One of the forms of knowledge acquisition in the current era is the distance education system, which has changed the traditional teaching methods, made it possible for everyone to learn everywhere and at any time, and has established social justice in the distribution of resources and facilities. It has created the necessary conditions for standardized education and in accordance with the needs of individuals and society, as well as the significant help that this system can easily and timely modernize education, save time, money and energy consumption, create opportunities for continuing education for employed people, strengthen specializations and creates calmness and reduces anxiety. And given that in addition to classroom teaching at the university, distance learning is now a valid method worldwide and UNESCO and other educational organizations around the world emphasize the expansion of distance learning, it is necessary to seriously develop it and the foundations of epistemology; and make it known to policymakers, planners and learners.The present study was conducted with the aim of identification and assessing the epistemological characteristics of MOOC (massive and courses). Methods: For this purpose, two methods of exploratory search (qualitative) and a questionnaire (quantitative) method were used. In the qualitative part of the research environment, the relevant electronic sources related to the subject matter of the research including 20 related articles were selected. In the quantitative section from the statistical population of 60 specialists in planning distance education in 2018 in the country a sample of 36 people was selected through voluntary sampling. To analyze the qualitative data, content analysis method and content validity index were used for analyzing quantitative data from mean weight and Friedman test. Findings: The results of content analysis indicated that four episodes of the learner, the content, teaching organization and educational environment can be investigated in MOOC epistemology (massive and courses). A total of 35 criteria were identified and confirmed. Quantitative results show that improving the level of information and digital literacy of professors, and knowledge with previous cognitive structures are the most important criterions of the epistemological characteristics of the courses of MOOC; and the criteria of ease of usedigital content, the recruitment of information technology professionals, for knowledge courses and the provision of Internet-based learning group environment, are the most important criterion for epistemology of massive MOOC. Conclusion: The results showed that in the epistemology of massive courses the dim   ===================================================================================== COPYRIGHTS  ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

Superconformal constraints for QCD conformal anomalies

Anomalous superconformal Ward identities and commutator algebra in N = 1 super-Yang-Mills theory give rise to constraints between the QCD special conformal anomalies of conformal composite operators. We evaluate the superconformal anomalies that appear in the product of renormalized conformal operators and the trace anomaly in the supersymmetric spinor current and check the constraints at one-loop order. In this way we prove the universality of QCD conformal anomalies, which define the non-diagonal part of the anomalous dimension matrix responsible for scaling violations of exclusive QCD amplitudes at the next-to-leading order.Comment: 30 pages, 2 figures, LaTe

Scheme dependence of NLO corrections to exclusive processes

We apply the so-called conformal subtraction scheme to predict perturbatively exclusive processes beyond leading order. Taking into account evolution effects, we study the scheme dependence for the photon-to-pion transition form factor and the electromagnetic pion form factor at next-to-leading order for different pion distribution amplitudes. Relying on the conformally covariant operator product expansion and using the known higher order results for polarized deep inelastic scattering, we are able to predict perturbative corrections to the hard-scattering amplitude of the photon-to-pion transition form factor beyond next-to-leading order in the conformal scheme restricted to the conformal limit of the theory.Comment: RevTeX, 25 pages, 2 figures, 5 tables, minor changes, to be published in Phys. Rev.

A multiloop improvement of non-singlet QCD evolution equations

An approach is elaborated for calculation of "all loop" contributions to the non-singlet evolution kernels from the diagrams with renormalon chain insertions. Closed expressions are obtained for sums of contributions to kernels $P(z)$ for the DGLAP equation and $V(x,y)$ for the "nonforward" ER-BL equation from these diagrams that dominate for a large value of $b_0$, the first $\beta$-function coefficient. Calculations are performed in the covariant $\xi$-gauge in a MS-like scheme. It is established that a special choice of the gauge parameter $\xi=-3$ generalizes the standard "naive nonabelianization" approximation. The solutions are obtained to the ER-BL evolution equation (taken at the "all loop" improved kernel), which are in form similar to one-loop solutions. A consequence for QCD descriptions of hard processes and the benefits and incompleteness of the approach are briefly discussed.Comment: 13 pages, revtex, 2 figures are enclosed as eps-file, the text style and figures are corrected following version, accepted for publication to Phys. Rev.