The effect of annealing on the elastoplastic and viscoelastic responses of isotactic polypropylene

Observations are reported on isotactic polypropylene (i) in a series of tensile tests with a constant strain rate on specimens annealed for 24 h at various temperatures in the range from 110 to 150 C and (ii) in two series of creep tests in the sub-yield region of deformation on samples not subjected to thermal treatment and on specimens annealed at 140 C. A model is developed for the elastoplastic and nonlinear viscoelastic responses of semicrystalline polymers. A polymer is treated an equivalent transient network of macromolecules bridged by junctions (physical cross-links, entanglements and lamellar blocks). The network is assumed to be highly heterogeneous, and it is thought of as an ensemble of meso-regions with different activation energies for separation of strands from temporary nodes. The elastoplastic behavior is modelled as sliding of meso-domains with respect to each other driven by mechanical factors. The viscoelastic response is attributed to detachment of active strands from temporary junctions and attachment of dangling chains to the network. Constitutive equations for isothermal uniaxial deformation are derived by using the laws of thermodynamics. Adjustable parameters in the stress-strain relations are found by fitting the experimental data.Comment: 29 pages, 14 figure

Injecting Shortcuts for Faster Running Java Code

Genetic Improvement of software applies search methods to existing software to improve the target program in some way. Impressive results have been achieved, including substantial speedups, using simple operations that replace, swap and delete lines or statements within the code. Often this is achieved by specialising code, removing parts that are unnecessary for particular use-cases. Previous work has shown that there is a great deal of potential in targeting more specialised operations that modify the code to achieve the same functionality in a different way. We propose six new edit types for Genetic Improvement of Java software, based on the insertion of break, continue and return statements. The idea is to add shortcuts that allow parts of the program to be skipped in order to speed it up. 10000 randomly-generated instances of each edit were applied to three open-source applications taken from GitHub. The key findings are: (1) compilation rates for inserted statements without surrounding "if" statements are 1.5-18.3%; (2) edits where the insert statement is embedded within an "if" have compilation rates of 3.2-55.8%; (3) of those that compiled, all 6 edits have a high rate of passing tests (Neutral Variant Rate), >60% in all but one case, and so have the potential to be performance improving edits. Finally, a preliminary experiment based on local search shows how these edits might be used in practice

Optimal k-space sampling for single point imaging of transient systems

A modification of the Single Point Imaging (SPI) is presented. The novel approach aims at increasing the sensitivity of the method and hence the resulting Signal-to-Noise ratio (SNR) for a given total time interval. With prior knowledge of the shape of the object under study, a selective sparse k-space sampling can then be used to follow dynamic phenomena of transient systems, in this case the absorption of moisture by a cereal-based wafer material. Further improvement in the image quality is achieved when the un-sampled k-space points are replaced by those of the initial dry or the final wet sample acquired at the beginning and the end of the acquisition respectively when there are no acquisition time limitations

Optimal k-space sampling for single point imaging of transient systems

A modification of the Single Point Imaging (SPI) is presented. The novel approach aims at increasing the sensitivity of the method and hence the resulting Signal-to-Noise ratio (SNR) for a given total time interval. With prior knowledge of the shape of the object under study, a selective sparse k-space sampling can then be used to follow dynamic phenomena of transient systems, in this case the absorption of moisture by a cereal-based wafer material. Further improvement in the image quality is achieved when the un-sampled k-space points are replaced by those of the initial dry or the final wet sample acquired at the beginning and the end of the acquisition respectively when there are no acquisition time limitations

Single-Polymer Composites (SPCs) : Status and Future Trends

Preparation, properties and applications of single-polymer composites (SPCs), representing an emerging family within the polymeric composite materials, have been surveyed. SPCs were classified in respect to their composition (one- and two-constituents), and preforms (non-consolidated and consolidated). SPCs composed of amorphous or semicrystalline matrices and semicrystalline reinforcements were considered. Methods to widen the temperature difference between the matrix- and reinforcement-giving materials of the same polymer (one-constituent) or same polymer type (two-constituent approach) have been introduced and discussed. Special attention was paid to the unsolved questions related to the interface/interphase in SPCs. It was emphasized that the development of SPCs is fuelled by the need of engineering parts in different applications which have low density and “ultimate” recyclability (i.e. reprocessing via remelting). Recent development of SPCs is supported by novel preform preparation, consolidation and production possibilities

Developing a role for patients and the public in the implementation of health and social care research evidence into practice: the PIPER study (Pathways to Implementation for Public Engagement in Research) realist evaluation protocol

Background While patients and the public are routinely involved as active collaborators in health and social care research, they are rarely involved in the implementation of research. The PIPER (Pathways to Implementation for Public Engagement in Research) research questions are: 1. How can patients, carers, service users and the public be involved in the implementation of health and social care research evidence into practice? 2. What types of roles, contributions and impact can patients, carers, service users and the public make to the implementation of health and social care evidence into practice? 3. How can we support patients, service users, carers and the public to contribute to the implementation of health and social care evidence into practice? 4. How can we co-produce the knowledge that explores a greater role for patients, carers, service users and the public in the implementation of health and social care evidence into practice? Methods Our overarching methodological framework is realist evaluation. This study includes four work packages with a cross-cutting co-production theme. •Work Package 1: A realist review of published literature, grey literature and sources such as blogs. •Work Package 2: Interviews with 40–60 people using a realist approach. •Work Package 3: A series of workshops to co-design the PIPER Toolkit. •Work Package 4: Pilot evaluation of the PIPER Toolkit. Results The scoping of the literature will be informed by the development of an initial programme theory that identifies the potential breadth of the field of public involvement in implementation. Data from the WP2 interviews will be used to iteratively refine the development of the context, mechanism and outcomes (CMOs). This will inform the PIPER Toolkit, which will consist of a set of ‘Guiding Principles’ supported by ‘Practical Resources.’ The PIPER Toolkit will enable an individual or a group to plan and undertake implementation activities. More specifically, the Guiding Principles will enable the Practical Resources to be tailored to specific implementation strategies for an individual or group. Discussion Patient and public involvement in implementation is an emerging area of practice and is likely to significantly strengthen over the next decade. The PIPER Toolkit will recognise this early stage of development, identifying the key system enablers that organisations need to have in place to support this activity. The Toolkit will support patients and the public and implementation teams to navigate the field of implementation practice. The PIPER study will challenge the field of implementation and knowledge mobilisation research to develop clearer forms of partnership with patients and the public in both research and practice