197,438 research outputs found
Towards a fuller understanding of selected molecular compounds
No full textThis work is separated into two distinct sections. The first section deals with the analysis by variable temperature single crystal X-ray diffraction of crystalline molecular materials with novel physical properties. The second section details the electron density analysis of selected crystalline compounds using high resolution, low temperature single crystal X-ray diffraction. Chapter 1 provides introduction to X-ray diffraction outlining the theory this work is based on. Chapter 2 introduces the molecular material studies based on materials containing the bis(ethylenedithio)-tetrathiaftilvalene molecule. The aim of these studies was to achieve a greater understanding of the materials and the changes they undergo when exposed to variations in temperature whilst in the crystalline state. These structural changes observed are very minor but have dramatic effects on the electrical properties of the materials studied. It became apparent that the only way to form a full understanding of these materials was to be able to 'see' the electronic configuration of the materials, not just their gross structure. The field of electron density analysis by X- ray diffraction is now a well documented area. Chapter 4 provides an introduction to the field of electron density analysis. Diffraction experiments were conducted on systems of different complexity to investigate this field and these results are reported in Chapter 5. No electron density analyses have been conducted on the molecular materials studied in Chapter 3 as yet, due to the lack of crystals of suitable quality. It was also noted that to fully categorise the nature of the physical changes occurring in these structures that a diffractometer capable of analysing these samples throughout the temperature range of their physical phenomena was needed. An outline for the development of such a diffractometer is detailed in Chapter 6, 'future works'
Amulets and Talismans of the Middle East and North Africa in Context
No full textIn this volume amulets and talismans are studied within a broader system of meaning that shapes how they were manufactured, activated and used in different networks. Text, material features and the environments in which these artifacts circulated, are studied alongside each other, resulting in an innovative approach to understand the many different functions these objects could fulfil in pre-modern times. Produced and used by Muslims and non-Muslims alike, the case studies presented here include objects that differ in size, material, language and shape. What the articles share is an all-round, in-depth approach that helps the reader understand the complexity of the objects discussed and will improve one’s understanding of the role they played within pre-modern societies. Contributors Hazem Hussein Abbas Ali, Gideon Bohak, Ursula Hammed, Juan Campo, Jean-Charles Coulon, Venetia Porter, Marcela Garcia Probert, Anne Regourd, Yasmine al-Saleh, Karl Schaefer and Petra M. Sijpesteijn
Langevin dynamics in constant pressure extended systems
No full textThe advantages of performing Langevin dynamics in extended systems are discussed. A simple Langevin dynamics scheme for producing the canonical ensemble is reviewed, and is then extended to the Hoover ensemble. We show that the resulting equations of motion generate the isobaric–isothermal ensemble. The Parrinello–Rahman ensemble is then discussed and we show that despite the presence of intrinsic probability gradients in this system, a Langevin dynamics approach samples the extended phase space in the correct fashion. The implementation of these methods in the ab initio plane wave density functional theory code CASTEP [M. D. Segall, P. L. D. Lindan, M. J. Probert, C. J. Pickard, P. J. Hasnip, S. J. Clarke, and M. C. Payne, J. Phys.: Condens. Matter 14, 2717 (2003)] is demonstrated
int_defects usage and validation examples
No full textThis dataset contains results of parametric finite element studies of structures containing crack-like flaws. All of the examples were created using the int_defects toolbox for MATLAB, which was designed for automating parametric finite element of this type. This toolbox and these associated examples are described in the following article: H. E. Coules & M. A. Probert, "Studying the interaction of crack-like flaws using the MATLAB toolbox int_defects", Engineering Fracture Mechanics
Optimal heat transfer design for district-heating and cooling pipelines in air-filled cavities
No full textDistrict-heating and/or cooling systems are gradually becoming
popular all over the world for heating and/or cooling of
large premises.
Current conventional practice for the DHC underground
distribution networks is to place the supply and the return pipelines
side-by-side in air-filled trencRe's. However, t present
investigation has shown that by optimising the location of the
pipelines, the thermal insulation provided by the air around the
pipes can be maximised. This is achieved by placing the hot pipeline
above the cold one, the exact position depending upon the
temperatures involved. For most purposes, it is recommended that
the displacement ratio for the hot pipe is to be at -0.7 or -0.08
and that of the cold pipe at 0.05 or 0.67 for district heating or
cooling respectively [i. e. the hot and cold pipes being placed in
the upper and lower halves of the trench respectively].
Each chapter is presented in such a way that it can be read
independently of the others as far as possible
Amulets and talismans of the Middle East and North Africa in context: transmission, efficacy and collections
No full textbookHorizon 2020(H2020)683194Middle Eastern Studie
int_defects toolbox v1.2.0
No full textint_defects is a toolbox for MATLAB which automates parametric finite element studies of structures containing crack-like flaws. It is free and open-source software distributed under the terms of the MIT license (see included license file). int_defects is described in the paper: H. E. Coules & M. A. Probert, "Studying the interaction of crack-like flaws using the MATLAB toolbox int_defects", Engineering Fracture Mechanics. Further details of the scope and capabilities of the toolbox are given in the User Guide which is included with this distribution
Seed dormancy and germination in three Crocus ser. Verni species (Iridaceae): implications for evolution of dormancy within the genus
No full textDr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
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