(E,E)-N1,N2-Bis(2,6-di­fluoro­benzyl­idene)ethane-1,2-di­amine.

The asymmetric unit of the title compound, C16H12F4N2, comprises half of the potentially bidentate Schiff base ligand, with an inversion centre located at the mid-point of the central C—C bond. The crystal packing is stabilized by inter­molecular C—H⋯N and π–π inter­actions [centroid–centroid distance = 3.6793 (12) Å and inter­planar spacing = 3.4999 (7) Å]

Critical Pedagogy in Architectural Design Course (case study: postgraduate design course (1) of Islamic Azad university of Gorgan)

Background and Objective:Creating a learning environment rich in social relationships in which peer interaction and collective learning can be developed is the core of the studio-based education for teaching architectural design. The social dimensions of the studio and the opportunities it provides for collaboration and participation serve as a stimulus for learning, and it is the culture of the studio that means sustainability to students. One of the interactive teaching methods that seems to be in line with the multiplicity of today's world and the different nature of architecture and the workshop education system is the critical pedagogy method invented by the Brazilian thinker Paolo Freire. Freire considers the main purpose of education to be the development of creative and critical human beings who look critically at all the thoughts, ideas and values ​​in society, as well as the actions of individuals and the way they deal with various events and happenings to find their roots. Freire's model in critical education mostly includes critical dialogue in which students (whole class) present their views and review evaluations and critiques. Participate in evaluating the thoughts of others and together with them, by combining views and examining arguments, take a more accurate and comprehensive approach to the issue and discover effective solutions. Therefore, it can be inferred that the critical education methodwith its special characteristics has the potential to improve the quality of architectural design classes. The aim of this study is to illustrate the procedure of applying critical pedagogy in Iran higher education context –architecture discipline- to identify challenges and improve the method in the selected environment. Methods:The qualitative method (interpretation) was selected as research method and content analysis was performed on the collected data. 24 postgraduate architecture students were selected as the sample, and by using a bipartite subject, comparison between two methods (traditional and critical) become possible. To verify and extend the model, the experiment was repeated next year with 22 different students. Findings: The results indicated that the effects of critical pedagogy have been perceived by students in eight categories: (1) improving intrinsic motivation (2) improving social skills, oral skills and self-confidence, (3) improving the speed and quality of development process of architectural ideas, (4) creating diversity and cheerfulness, (5) reducing stress and anxiety, (6) waste of time and vain discussions, (7) educational marginalization, and (8) self-censorship. The first 5 categories are positive feedbacks and the other three are negative feedbacks considered as challenges of applying critical pedagogy. At the end, some strategies are purposed to overcome these challenges and improve the quality of the classes. Conclusion:Some solutions to overcome the challenges are suggested including: students choosing an external reality topic, phasing group corrections, continuing the method to institutionalize it, changing students' view of the teacher as the source of information or the professor as a superior and miraculous person and change the view and reduce students' distrust of themselves. Characteristics for the critical teacher are also mentioned, such as humility, humor, high capacity of the teacher against laughter and jokes, great patience of the teacher in the face of useless discussions, and familiarity of the critical teacher with theories of psychology and psychoanalysis.   ===================================================================================== COPYRIGHTS  ©2019 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.  ====================================================================================

One-dimensional Modelling and Optimisation of an Industrial Steam Methane Reformer

Steam methane reforming is one of the most promising processes to convert natural gas into valuable products such as hydrogen. In this study, a one-dimensional model was used to model and optimise an industrial steam methane reformer, using mass and thermal balances coupled with pressure drop in the reformer tube. The proposed model was validated by the experimental data. Furthermore, the effects of flowrate and temperature of the feed, tube wall temperature, and tube dimension on the reformer performance were studied. Finally, a multiobjective optimisation was done for methane slip minimisation and hydrogen production maximisation using genetic algorithm. The results illustrated the optimum feed flowrate of 2761.9 kmol h–1 (minimum 32 mol.% produced hydrogen and maximum 0.15 mol.% unreacted methane). This is one of the few studies on investigation of steam methane reformer using a simple and effective model, and genetic algorithm. This work is licensed under a Creative Commons Attribution 4.0 International License

Operational maps between molecular properties and environmental stress cracking resistance (ESCR)

This is the peer reviewed version of the following article: Sardashti, P., Stewart, K. M. E., Polak, M., Tzoganakis, C., & Penlidis, A. (2019). Operational maps between molecular properties and environmental stress cracking resistance. Journal of Applied Polymer Science, 136(4), 47006. https://doi.org/10.1002/app.47006, which has been published in final form at https://doi.org/10.1002/app.47006. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Environmental stress cracking (ESC) is one of the main failure mechanisms involved in polymer fractures. This paper focusses on the environmental stress cracking resistance (ESCR) of polyethylene (PE) in which ESC occurs through a slow crack growth mechanism. In order to predict the ESCR of PE, it is necessary to fully understand the molecular structure of the resin. This paper demonstrates the relationships between molecular structure characteristics and material responses based on experimental characterization and published literature trends. Relationships between ESCR, molecular weight (MW), percentage crystallinity, and density were used to create ESCR and molecular structure maps, which can be used to improve the development of PE resins with a desirable (better/higher) ESCR. These maps along with a logical flow chart offer practical prescriptions and describe pathways towards the development of PE with a desirable ESCR. In addition, this paper presents case studies that demonstrate the effectiveness of this approach.The authors gratefully acknowledge financial support from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Canada Research Chair (CRC) program, and the Ontario Graduate Scholarship (OGS) program. Many thanks also go to Imperial Oil Limited, Sarnia, ON, Canada, for financial support and for providing resins for the study over many years

Touch\'e: Towards Ideal and Efficient Cache Compression By Mitigating Tag Area Overheads

Compression is seen as a simple technique to increase the effective cache capacity. Unfortunately, compression techniques either incur tag area overheads or restrict data placement to only include neighboring compressed cache blocks to mitigate tag area overheads. Ideally, we should be able to place arbitrary compressed cache blocks without any placement restrictions and tag area overheads. This paper proposes Touch\'e, a framework that enables storing multiple arbitrary compressed cache blocks within a physical cacheline without any tag area overheads. The Touch\'e framework consists of three components. The first component, called the ``Signature'' (SIGN) engine, creates shortened signatures from the tag addresses of compressed blocks. Due to this, the SIGN engine can store multiple signatures in each tag entry. On a cache access, the physical cacheline is accessed only if there is a signature match (which has a negligible probability of false positive). The second component, called the ``Tag Appended Data'' (TADA) mechanism, stores the full tag addresses with data. TADA enables Touch\'e to detect false positive signature matches by ensuring that the actual tag address is available for comparison. The third component, called the ``Superblock Marker'' (SMARK) mechanism, uses a unique marker in the tag entry to indicate the occurrence of compressed cache blocks from neighboring physical addresses in the same cacheline. Touch\'e is completely hardware-based and achieves an average speedup of 12\% (ideal 13\%) when compared to an uncompressed baseline.Comment: Keywords: Compression, Caches, Tag Array, Data Array, Hashin

A path integral methodology for obtaining thermodynamic properties of nonadiabatic systems using Gaussian mixture distributions

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Raymond, N., Iouchtchenko, D., Roy, P.-N., & Nooijen, M. (2018). A path integral methodology for obtaining thermodynamic properties of nonadiabatic systems using Gaussian mixture distributions. The Journal of Chemical Physics, 148(19), 194110 and may be found at https://doi.org/10.1063/1.5025058We introduce a new path integral Monte Carlo method for investigating nonadiabatic systems in thermal equilibrium and demonstrate an approach to reducing stochastic error. We derive a general path integral expression for the partition function in a product basis of continuous nuclear and discrete electronic degrees of freedom without the use of any mapping schemes. We separate our Hamiltonian into a harmonic portion and a coupling portion; the partition function can then be calculated as the product of a Monte Carlo estimator (of the coupling contribution to the partition function) and a normalization factor (that is evaluated analytically). A Gaussian mixture model is used to evaluate the Monte Carlo estimator in a computationally efficient manner. Using two model systems, we demonstrate our approach to reduce the stochastic error associated with the Monte Carlo estimator. We show that the selection of the harmonic oscillators comprising the sampling distribution directly affects the efficiency of the method. Our results demonstrate that our path integral Monte Carlo method’s deviation from exact Trotter calculations is dominated by the choice of the sampling distribution. By improving the sampling distribution, we can drastically reduce the stochastic error leading to lower computational cost.Natural Sciences and Engineering Research Council of Canada (NSERC) Ontario Ministry of Research and Innovation (MRI) Canada Foundation for Innovation (CFI) Canada Research Chair progra

A comprehensive survey of the analytical, numerical and experimental methodologies for dynamics of multibody mechanical systems with clearance or imperfect joints

"Available online 19 December 2017"A comprehensive survey of the literature of the most relevant analytical, numerical, and experimental approaches for the kinematic and dynamic analyses of multibody mechanical systems with clearance joints is presented in this review. Both dry and lubricated clearance joints are addressed here, and an effort is made to include a large number of research works in this particular field, which have been published since the 1960′s. First, the most frequently utilized methods for modeling planar and spatial multibody mechanical systems with clearance joints are analyzed, and compared. Other important phenomena commonly associated with clearance joint models, such as wear, non-smooth behavior, optimization and control, chaos, and uncertainty and links’ flexibility, are then discussed. The main assumptions procedures and conclusions for the different methodologies are also examined and compared. Finally, future developments and new applications of clearance joint modeling and analysis are highlighted.This research was supported in part by the China 111 Project (B16003) and the National Natural Science Foundation of China under Grants 11290151, 11472042 and 11221202. The work was also supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

Early stages of oxide growth in H-terminated silicon nanowires: determination of kinetic behavior and activation energy

Silicon nanowires (Si NWs) terminated with hydrogen atoms exhibit higher activation energy under ambient conditions than equivalent planar Si(100). The kinetics of sub-oxide formation in hydrogen-terminated Si NWs derived from the complementary XPS surface analysis attribute this difference to the Si-Si backbond and Si-H bond propagation which controls the process at lower temperatures (T = 200 degrees C), the activation energy was similar due to self-retarded oxidation. This finding offers the understanding of early-stage oxide growth that affects the conductance of the near-gap channels leading towards more efficient Si NW electronic devices