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Traditionally, Biot's formulation is employed to model the behavior of saturated soils. The u - p w (solid displacement–pore water pressure) formulation can be considered as the standard one, since involves a good computational performance together with excellent accuracy for slow and moderate speed phenomena. Dynamic processes can be studied even if the acceleration of the water is neglected, what occurs in the undrained limit. It is well-known that u - p w formulation might display instabilities in the undrained-incompressible limit. Several techniques have been proposed to overcome this issue, principally within an implicit time integration scheme for small strains. In this paper, a robust implementation of the divergence of the momentum equation technique is presented for an explicit u - p w approach within the framework of optimal transportation meshfree scheme at finite strain. Several examples are provided in order to assess the good performance of the proposed methodology. [ABSTRACT FROM AUTHOR]

This study is aimed at exploring ninth-grade Bhutanese students' views of nature of science (NOS). A total of 389 students from middle secondary and higher secondary schools from the eastern, western, southern and central regions of Bhutan took part in this study. To generate a representative population, a stratified random sampling technique was used. An adopted and adapted version of the Students Understanding of Science and Scientific Inquiry (SUSSI) comprised Likert-type items, and open-ended questions were used as a research tool. Quantitative data were analysed using descriptive statistics, and the qualitative data were analysed and categorized into naïve, transitional and informed views. The results indicated that the majority of the Bhutanese students held naïve views on sociocultural embeddedness, scientific laws, scientific theories and science as a body of knowledge. The study has an implication for curriculum developers and teaching professionals, particularly in culturally rich countries, that explicit instruction of NOS should be reframed based on students' cultural backgrounds and their indigenous knowledge. [ABSTRACT FROM AUTHOR]

In this paper a new methodology to simulate saturated soils subjected to dynamic loadings under large deformation regime (locally up to 40% in equivalent plastic strain) is presented. The coupling between solid and fluid phases is solved through the complete formulation of the Biot’s equations. The additional novelty lies in the employment of an explicit time integration scheme of the u-w (solid displacement-relative fluid displacement) formulation which enables us to take advantage of such explicit schemes. Shape functions based on the principle of maximum entropy implemented in the framework of Optimal Transportation Meshfree schemes are utilized to solve both elastic and plastic problems. [ABSTRACT FROM AUTHOR]

A new elastoplastic J 2 − flow model with nonlinear combined hardening is proposed for the purpose of achieving an explicit, comprehensive simulation of pseudo-elastic SMAs over the whole range of strain up to failure. To this goal, a new, explicit methodology based on any given uniaxial data is introduced to obtain multi-axial expressions for the constitutive quantities incorporated in this model, in such a unified sense that all three successive deformation stages may be simultaneously represented, including a pseudo-elastic stage with perfect strain recovery, a hardening stage with partial strain recovery, and a softening stage up to failure. As such, any given shapes of uniaxial stress–strain curves from both loading and unloading in these three stages may be automatically reproduced from the proposed model, without involving usual complicated numerical procedures in treating nonlinear rate constitutive equations with a number of switching conditions. Numerical examples with test data are supplied to simulate a complete process including all three stages. [ABSTRACT FROM AUTHOR]

This paper reports the results obtained in the test of a proposal for the teaching of history and philosophy of science to Higher Education students enrolled in courses on natural sciences. The proposal takes actual historical examples as a basis for eliciting discussions about philosophical issues. It amounts to an explicit approach, directly addressing epistemological contents, which was elaborated and tested from the perspective of a teacher-researcher. The proposal was tested through a quali-quantitative approach. Data were gathered in a class of a course on history and philosophy of science for Biology majors, through the questionnaire VNOS-C (Views of the Nature of Science, Form C), at the beginning and end of a term. They were qualitatively treated by analyzing categories built from the answers given by the students. Based on some issues agreed upon by several post-positivist theories of science, we evaluated the adequacy of the students’ epistemological views, obtaining scores for each question, the sum of which resulted in a total score for each questionnaire. The effects of the proposal on the students’ views were analyzed qualitative and quantitatively by means of a discussion of the frequencies of adequate, partially adequate, and inadequate answers to each question and a statistical test comparing the total scores of each student, in the pre- and post-tests. To analyze the effects on each epistemological aspect addressed in the questionnaire, we performed tests comparing the scores obtained by the students in each question, at the beginning and end of the term. Generally speaking, the proposal resulted in an evolution of the views about the nature of science of all students who did both the pre- and post-tests. It was more effective in promoting a change in views about the demarcation between science and other ways of knowing, the differences between laws and theories, and the relationship between models and evidence. Nevertheless, it had a more limited success in the case of views about what is an experiment, the requirement of experimental methods in scientific practice, the causes of theoretical change, and the possibility of drawing different conclusions from the same data.

Well-known models for rubberlike elasticity with strain-stiffening effects provide good predictions for unlimitedly, rapidly growing stress in a process of approaching a very large strain limit. According to such models, however, unbounded elastic strain energy would be generated as the strain limit is approached. To resolve this issue, a new, explicit approach is proposed to obtain multi-axial elastic potentials based on uniaxial data and shear data. Then, a strain-stiffening elastic potential is given to always yield bounded strain energy. Good agreement is achieved with a number of test data. [ABSTRACT FROM AUTHOR]

This study is concerned with a new, explicit approach by means of which forms of the large strain elastic potential for multiaxial rubberlike elasticity may be obtained based on data for a single deformation mode. As a departure from usual studies, here for the first time errors may be estimated and rendered minimal for all possible deformation modes and, furthermore, failure behavior may be incorporated. Numerical examples presented are in accurate agreement with Treloar's well-known data. [ABSTRACT FROM AUTHOR]

This study examines conceptual change in some aspects of nature of science (NOS) in undergraduate students after learning through the explicit approach. NOS is an essential component in the Thai curriculum and is required knowledge for science teachers. Forty-one undergraduate students who study in the teacher education program participated in this classroom action research. Students' understanding of various aspects of NOS was assessed, including the empirical and tentative nature of scientific knowledge, the nature of science experiment, and the nature of scientific law and theory. To examine the pre-instruction view of NOS, some items of Views of Nature of Science Questionnaire-Form C (VNOS-C), developed by Fouad Abd-El-Khalick were administered to the students. Using crossitems analysis, the results indicated that most of them held naïve ideas of NOS in all aspects. For example, they believed that law is different from theory because law is certain while theory is not. The students' conceptions of NOS dramatically changed after learning with the explicit approach, which was reported to be an effective strategy to teach NOS. The instruction included explicit discussion of science history, group study of scientific articles, and use of models and analogies as the tools for reflective discussion on scientific theory and law. To describe how the students had changed their conceptions of NOS, the percentage of students' responses are reported and discussed. In order to examine the effectiveness of the learning activities in the cognitive aspects, binomial analysis was conducted to compare the students' understanding with the expected criteria. The student's satisfaction with all learning activities was also at a high level. The results of this study support the idea of using the explicit approach in teaching NOS. [ABSTRACT FROM AUTHOR]

Highlights: [•] Direct, explicit approach to modeling SMA pseudo-elasticity. [•] New nonlinear hardening rule with substantial coupling. [•] Thermodynamic restrictions are rendered free and explicit. [•] Direct, explicit approach to matching realistic hysteresis loops of any given shape. [•] Bypassing usual complicated procedures for identifying a large set of unknown parameters. [ABSTRACT FROM AUTHOR]

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The purpose of this study was to investigate changes in preservice teachers’ understanding of the nature of science (NOS) as a result of four activity-based interventions that represent three instructional approaches used in a middle grades science methods course. Ten participants’ understanding of NOS and their perceptions about the activity-based interventions were investigated. Data were collected using open-ended questionnaires and in-depth interviews before and after the interventions. Written artifacts and recorded group discussions were collected during the interventions. The results of this study showed that inclusion of various approaches to teaching NOS can contribute to developing preservice teachers’ understanding of NOS. The activities complemented each other in the teaching of the NOS components. In addition, the preservice teachers perceived that the four interventions were helpful in improving their understanding of NOS and in preparing them for future teaching. [ABSTRACT FROM AUTHOR]

• A new method for design of complex reinforced concrete structures is presented. • The method is based on strength reduction and consistent with the Strut & Tie method. • Re-organisation of struts in concrete occurs in a degradation phase. • A modified equation from the modified compression field theory is used. • Application examples demonstrate the feasibility / potential of the new approach. The design of complex reinforced concrete structures or elements of structures can be a challenging task for practitioner structural engineers in some specific non-conventional projects. For these specific cases, the use of well-established and standard design methods such as sectional methods or strut-and-tie methods can result into complex and sometimes inappropriate designs. On the other hand, the use of sophisticated numerical methods such as nonlinear finite element methods is not common in these situations because of their complexity and the lack of consensus on their validity within the engineering community. This work presents an innovative new design approach for complex reinforced concrete structures. The approach is inspired from the strength reduction numerical method, well-established in the field of slope stability in geotechnical engineering. It can be considered as an intermediate approach between the conservative and universally well accepted strut-and-tie method, and the powerful nonlinear finite element method. A new simple constitutive law for concrete has been developed for that purpose as a user subroutine under the software ABAQUS-Explicit. It allows for the degradation of concrete by gradually reducing its tensile strength during the analysis. This law is presented within an overall new framework for the design of reinforced concrete structure based on two steps. The structure is loaded in a first linear elastic step and then degradation of the tensile post-pic occurs in a second nonlinear step. At the end of this second step, a re-organisation of the internal stresses occurs within the structure. A resisting pattern and failure modes similar to those in the strut and tie models occur as well. Two application examples are presented at the end of the study and demonstrate the potential and the feasibility of the new approach. [ABSTRACT FROM AUTHOR]