Development of Casbar: a Two-phase Flow Code for the Interior Ballistics Problem

Accurate modelling of gun interior ballistic processes aids in the design and analysis of guns and their propelling charges. Presently, the most accurate modelling of the interior ballistics problem is provided by two-phase, multidimensional computational fluid dynamics (CFD) codes. We present our development of a CFD code, Casbar, which solves a two-phase (gas/particulate) flow problem in axisymmetric geometries. Our model is based on the governing equations for two-phase flow derived from separated flow theory. A finite-volume discretisation of the governing equations is used. The resulting set of equations is solved with a timestep-splitting approach based on the separation of various physical processes. We also present the modelling for the component physics such as propellant combustion and interphase drag. In addition, the solver includes the motion of the projectile and its influence on the flow dynamics. The capabilities of the code are demonstrated with some verification exercises

Adapting Translational Research Methods to Water, Sanitation, and Hygiene

Translational research applies scientific techniques to achieve practical outcomes, connecting pure research and pure practice. Many translational research types have arisen since the mid-1900s, reflecting the need to better integrate scientific advancement with policy and practice. Water, sanitation, and hygiene (WaSH) development efforts have aimed to reduce morbidity and mortality and improve service delivery; thus, associated research has a strong orientation toward applied studies that use diverse methods to support decision-making. Drawing from knowledge that emerged to support other professional fields, such as manufacturing and clinical healthcare, we characterize different types of translational research and clarify nomenclature and principles. We describe study approaches relevant to translational research questions, and offer overarching recommendations, specific examples, and resources for further study as practical advice to professionals who seek to apply translational methods to WaSH problems. To enhance collective outcomes, professionals should mindfully align projects within the translational spectrum. We further recommend overarching good practices such as documenting intervention adaptations, overtly considering contextual factors, and better distinguishing efficacy from effectiveness research by replicating studies in different contexts. By consciously improving the compatibility and linkages between WaSH science and practice, this guide can accelerate urgently needed progress toward global development goals

Comparison of type 2 diabetes prevalence estimates in Saudi Arabia from a validated Markov model against the International Diabetes Federation and other modelling studies

AbstractAimsTo compare the estimates and projections of type 2 diabetes mellitus (T2DM) prevalence in Saudi Arabia from a validated Markov model against other modelling estimates, such as those produced by the International Diabetes Federation (IDF) Diabetes Atlas and the Global Burden of Disease (GBD) project.MethodsA discrete-state Markov model was developed and validated that integrates data on population, obesity and smoking prevalence trends in adult Saudis aged ≥25 years to estimate the trends in T2DM prevalence (annually from 1992 to 2022). The model was validated by comparing the age- and sex-specific prevalence estimates against a national survey conducted in 2005.ResultsPrevalence estimates from this new Markov model were consistent with the 2005 national survey and very similar to the GBD study estimates. Prevalence in men and women in 2000 was estimated by the GBD model respectively at 17.5% and 17.7%, compared to 17.7% and 16.4% in this study. The IDF estimates of the total diabetes prevalence were considerably lower at 16.7% in 2011 and 20.8% in 2030, compared with 29.2% in 2011 and 44.1% in 2022 in this study.ConclusionIn contrast to other modelling studies, both the Saudi IMPACT Diabetes Forecast Model and the GBD model directly incorporated the trends in obesity prevalence and/or body mass index (BMI) to inform T2DM prevalence estimates. It appears that such a direct incorporation of obesity trends in modelling studies results in higher estimates of the future prevalence of T2DM, at least in countries where obesity has been rapidly increasing

Age-specific trends in cardiovascular mortality rates in the Netherlands between 1980 and 2009

Recent analyses suggest the decline in coronary heart disease mortality rates is slowing in younger age groups in countries such as the US and the UK. This work aimed to analyse recent trends in cardiovascular mortality rates in the Netherlands. Analysis was of annual all circulatory, ischaemic heart disease (IHD), and cerebrovascular disease mortality rates between 1980 and 2009 for the Netherlands. Data were stratified by sex and 10-year age group (age 35–85+). The annual rate of change and significant changes in the trend were identified using joinpoint Poisson regression. For almost all age and sex groups examined the rate of IHD and cerebrovascular disease mortality in the Netherlands has more than halved between 1980 and 2009. The decline in mortality from both IHD and cerebrovascular disease is continuing for all ages and sex groups, with anacceleration in the decline apparent from the late 1990s/early 2000s. The decline in age-specific all circulatory, coronary heart disease and cerebrovascular disease mortality rates continues for all age and sex groups in the Netherlands

Preventing type 2 diabetes mellitus in Qatar by reducing obesity, smoking, and physical inactivity: mathematical modeling analyses.

BACKGROUND: The aim of this study was to estimate the impact of reducing the prevalence of obesity, smoking, and physical inactivity, and introducing physical activity as an explicit intervention, on the burden of type 2 diabetes mellitus (T2DM), using Qatar as an example. METHODS: A population-level mathematical model was adapted and expanded. The model was stratified by sex, age group, risk factor status, T2DM status, and intervention status, and parameterized by nationally representative data. Modeled interventions were introduced in 2016, reached targeted level by 2031, and then maintained up to 2050. Diverse intervention scenarios were assessed and compared with a counter-factual no intervention baseline scenario. RESULTS: T2DM prevalence increased from 16.7% in 2016 to 24.0% in 2050 in the baseline scenario. By 2050, through halting the rise or reducing obesity prevalence by 10-50%, T2DM prevalence was reduced by 7.8-33.7%, incidence by 8.4-38.9%, and related deaths by 2.1-13.2%. For smoking, through halting the rise or reducing smoking prevalence by 10-50%, T2DM prevalence was reduced by 0.5-2.8%, incidence by 0.5-3.2%, and related deaths by 0.1-0.7%. For physical inactivity, through halting the rise or reducing physical inactivity prevalence by 10-50%, T2DM prevalence was reduced by 0.5-6.9%, incidence by 0.5-7.9%, and related deaths by 0.2-2.8%. Introduction of physical activity with varying intensity at 25% coverage reduced T2DM prevalence by 3.3-9.2%, incidence by 4.2-11.5%, and related deaths by 1.9-5.2%. CONCLUSIONS: Major reductions in T2DM incidence could be accomplished by reducing obesity, while modest reductions could be accomplished by reducing smoking and physical inactivity, or by introducing physical activity as an intervention

Recommending Learning Videos for MOOCs and Flipped Classrooms

[EN] New teaching approaches are emerging in higher education, such as flipped classrooms. In addition, academic institutions are offering new types of training like Massive Online Open Courses. Both of these new ways of education require high-quality learning objects for their success, with learning videos being the most common to provide theoretical concepts. This paper describes a hybrid learning recommender system based on content-based techniques, which is able to recommend useful videos to learners and teachers from a learning video repository. This hybrid technique has been successfully applied to a real scenario such as the central video repository of the Universitat Politècnica de València.This work was partially supported by MINECO/FEDER RTI2018-095390-B-C31 and TIN2017-89156-R projects of the Spanish government, and PROMETEO/2018/002 project of Generalitat Valenciana. J. Jordán and V. Botti are funded by UPV PAID-06-18 project. J. Jordán is also funded by grant APOSTD/2018/010 of Generalitat Valenciana - Fondo Social Europeo.Jordán, J.; Valero Cubas, S.; Turró, C.; Botti Navarro, VJ. (2020). Recommending Learning Videos for MOOCs and Flipped Classrooms. Springer. 146-157. https://doi.org/10.1007/978-3-030-49778-1_12S146157Blei, D.M., Ng, A.Y., Jordan, M.I.: Latent Dirichlet allocation. J. Mach. Learn. Res. 3, 993–1022 (2003)Bobadilla, J., Serradilla, F., Hernando, A.: Collaborative filtering adapted to recommender systems of e-learning. Knowl.-Based Syst. 22(4), 261–265 (2009)Burke, R.: Hybrid recommender systems: survey and experiments. User Model. User-Adap. Inter. 12(4), 331–370 (2002)Chen, W., Niu, Z., Zhao, X., Li, Y.: A hybrid recommendation algorithm adapted in e-learning environments. World Wide Web 17(2), 271–284 (2012). https://doi.org/10.1007/s11280-012-0187-zvan Dijck, J., Poell, T.: Higher education in a networked world: European responses to U.S. MOOCs. Int. J. Commun.: IJoC 9, 2674–2692 (2015)Dwivedi, P., Bharadwaj, K.K.: e-learning recommender system for a group of learners based on the unified learner profile approach. Expert Syst. 32(2), 264–276 (2015)Herlocker, J., Konstan, J., Terveen, L., Riedl, J.: Evaluating collaborative filtering recommender systems. ACM Trans. Inf. Syst. 22(1), 5–53 (2004)Institute and Committee of Electrical and Electronics Engineers: Learning Technology Standards: IEEE Standard for Learning Object Metadata. IEEE Standard 1484.12.1 (2002)Klašnja-Milićević, A., Ivanović, M., Nanopoulos, A.: Recommender systems in e-learning environments: a survey of the state-of-the-art and possible extensions. Artif. Intell. Rev. 44(4), 571–604 (2015). https://doi.org/10.1007/s10462-015-9440-zMaassen, P., Nerland, M., Yates, L. (eds.): Reconfiguring Knowledge in Higher Education. Higher Education Dynamics, vol. 50. Springer, Heidelberg (2018). https://doi.org/10.1007/978-3-319-72832-2MLLP research group, Universitat Politècnica de València: Tlp: The translectures-upv platform. http://www.mllp.upv.es/tlpO’Flaherty, J., Phillips, C.: The use of flipped classrooms in higher education: a scoping review. Internet High. Educ. 25, 85–95 (2015)Richardson, M., Dominowska, E., Ragno, R.: Predicting clicks: estimating the click-through rate for new ads. In: Proceedings of the 16th international conference on World Wide Web, pp. 521–530 (2007)Rodríguez, P., Heras, S., Palanca, J., Duque, N., Julián, V.: Argumentation-based hybrid recommender system for recommending learning objects. In: Rovatsos, M., Vouros, G., Julian, V. (eds.) EUMAS/AT -2015. LNCS (LNAI), vol. 9571, pp. 234–248. Springer, Cham (2016). https://doi.org/10.1007/978-3-319-33509-4_19Roehl, A., Reddy, S.L., Shannon, G.J.: The flipped classroom: an opportunity to engage millennial students through active learning strategies. J. Fam. Consum. Sci. 105, 44–49 (2013)Salton, G., Buckley, C.: Term-weighting approaches in automatic text retrieval. Inf. Process. Manag. 24(5), 513–523 (1988)Stoica, A.S., Heras, S., Palanca, J., Julian, V., Mihaescu, M.C.: A semi-supervised method to classify educational videos. In: Pérez García, H., Sánchez González, L., Castejón Limas, M., Quintián Pardo, H., Corchado Rodríguez, E. (eds.) HAIS 2019. LNCS (LNAI), vol. 11734, pp. 218–228. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-29859-3_19Tarus, J.K., Niu, Z., Yousif, A.: A hybrid knowledge-based recommender system for e-learning based on ontology and sequential pattern mining. Future Gener. Comput. Syst. 72, 37–48 (2017)Tucker, B.: The flipped classroom. Online instruction at home frees class time for learning. Educ. Next Winter 2012, 82–83 (2012)Turcu, G., Heras, S., Palanca, J., Julian, V., Mihaescu, M.C.: Towards a custom designed mechanism for indexing and retrieving video transcripts. In: Pérez García, H., Sánchez González, L., Castejón Limas, M., Quintián Pardo, H., Corchado Rodríguez, E. (eds.) HAIS 2019. LNCS (LNAI), vol. 11734, pp. 299–309. Springer, Cham (2019). https://doi.org/10.1007/978-3-030-29859-3_26Turró, C., Morales, J.C., Busquets-Mataix, J.: A study on assessment results in a large scale flipped teaching experience. In: 4th International Conference on Higher Education Advances (HEAD 2018), pp. 1039–1048 (2018)Turró, C., Despujol, I., Busquets, J.: Networked teaching, the story of a success on creating e-learning content at Universitat Politècnica de València. EUNIS J. High. Educ. (2014)Zajda, J., Rust, V. (eds.): Globalisation and Higher Education Reforms. GCEPR, vol. 15. Springer, Cham (2016). https://doi.org/10.1007/978-3-319-28191-

Effect of under-reinforcement on the flexural strength of corroded beams

Reinforced concrete beams are normally designed as under-reinforced to provide ductile behaviour i.e. the tensile moment of resistance, Mt(0) is less than the moment of resistance of the compressive zone, Mc. The degree of under-reinforcement (Mt(0)/Mc ratio) can depend upon the preferences of the designer in complying with design and construction constraints, codes and availability of steel reinforcement diameters and length. Mt(0)/Mc is further influenced during service life by corrosion which decreases Mt(0). The paper investigates the influence of Mt(0)/Mc on the residual flexural strength of corroded beams and determines detailing parameters (e.g. size and percentage of steel reinforcement, cover) on Mt(0)/Mc. Corroded reinforced concrete beams (100 mm · 150 mm deep) with varying Mt(0)/Mc ratios were tested in flexure. The results of the investigation were combined with the results of similar work by other researchers and show that beams with lower Mt(0)/Mc ratios suffer lower flexural strength loss when subjected to tensile reinforcement corrosion. Cover to the main steel does not directly influence Mt(0)/Mc and, thus, the residual flexural strength of corroded beams is not normally affected by increased cover. A simplified expression for estimating the residual strength of corroded beams is also given

The Fundamental Diagram of Pedestrian Movement Revisited

The empirical relation between density and velocity of pedestrian movement is not completely analyzed, particularly with regard to the `microscopic' causes which determine the relation at medium and high densities. The simplest system for the investigation of this dependency is the normal movement of pedestrians along a line (single-file movement). This article presents experimental results for this system under laboratory conditions and discusses the following observations: The data show a linear relation between the velocity and the inverse of the density, which can be regarded as the required length of one pedestrian to move. Furthermore we compare the results for the single-file movement with literature data for the movement in a plane. This comparison shows an unexpected conformance between the fundamental diagrams, indicating that lateral interference has negligible influence on the velocity-density relation at the density domain $1 m^{-2}<\rho<5 m^{-2}$. In addition we test a procedure for automatic recording of pedestrian flow characteristics. We present preliminary results on measurement range and accuracy of this method.Comment: 13 pages, 9 figure

Direction of light propagation to order G^2 in static, spherically symmetric spacetimes: a new derivation

A procedure avoiding any integration of the null geodesic equations is used to derive the direction of light propagation in a three-parameter family of static, spherically symmetric spacetimes within the post-post-Minkowskian approximation. Quasi-Cartesian isotropic coordinates adapted to the symmetries of spacetime are systematically used. It is found that the expression of the angle formed by two light rays as measured by a static observer staying at a given point is remarkably simple in these coordinates. The attention is mainly focused on the null geodesic paths that we call the "quasi-Minkowskian light rays". The vector-like functions characterizing the direction of propagation of such light rays at their points of emission and reception are firstly obtained in the generic case where these points are both located at a finite distance from the centre of symmetry. The direction of propagation of the quasi-Minkowskian light rays emitted at infinity is then straightforwardly deduced. An intrinsic definition of the gravitational deflection angle relative to a static observer located at a finite distance is proposed for these rays. The expression inferred from this definition extends the formula currently used in VLBI astrometry up to the second order in the gravitational constant G.Comment: 19 pages; revised introduction; added references for introduction; corrected typos; published in Class. Quantum Gra