On the importance of specific interface area in clay nanocomposites of PMMA filled with synthetic nano-mica

In clay nanocomposites, the specific interface area is the key factor determining potential improvements of properties. Nevertheless, in most systematic studies of nanocomposites little emphasis is put on assuring and characterizing dispersion quality. To probe the influence of dispersion quality, we compare nanocomposites filled with two layered silicates which were made by melt compounding and solution blending, respectively. Poly(methyl methacrylate) (PMMA) is chosen here as a thermoplastic model matrix which was compounded with a synthetic nano-mica (O-hect) and commercial Bentone with typical diameters of 5–7 μm and <300 nm, respectively.     

Value creation through project risk management

Risk management is a common and widely adopted project practice. Practitioners use risk management based on a common assumption that risk management adds value to projects. Yet, in the complex and ambiguous environment of a project, value is often subjective. If this is the case, then how do stakeholders perceive project risk management to create value? This paper presents a literature review and an empirical study of project risk management as a means of creating value. The empirical study is based on interviews, analyzed through qualitative analysis, to unravel the subjective value of project risk management. Specifically, we addressed how practitioners perceived the connection between project risk management practices and value creation. We found that stakeholders' perceptions of value played an important role in how value was created through project risk management. What a stakeholder perceives to be important, such as the prospective outcomes of a project, influences the perceived value of a given project risk management practice. The empirical findings indicate the need for a contextualized understanding of the value of project risk management, and thereby provide a more nuanced view of the variety of forms through which project risk management can create value. The findings question the “universal ideal” of PRM value creation portrayed in the academic and practitioner literature.     

Lattice-based certificateless public-key encryption in the standard model

The notion of certificateless public-key encryption (CL-PKE) was introduced by Al-Riyami and Paterson in 2003 that avoids the drawbacks of both traditional PKI-based public-key encryption (i.e., establishing public-key infrastructure) and identity-based encryption (i.e., key escrow). So CL-PKE like identity-based encryption is certificate-free, and unlike identity-based encryption is key escrow-free. In this paper, we introduce simple and efficient CCA-secure CL-PKE based on (hierarchical) identity-based encryption. Our construction has both theoretical and practical interests. First, our generic transformation gives a new way of constructing CCA-secure CL-PKE. Second, instantiating our transformation using lattice-based primitives results in a more efficient CCA-secure CL-PKE than its counterpart introduced by Dent in 2008.     

Some aspects on ruggedness of SiC power devices

This article is on effects that can destroy SiC power semiconductor devices. The failure physics in SiC devices are discussed based on the well understood effects in silicon devices. In some device properties, such as surge current, short circuit, static avalanche and dynamic avalanche, SiC has significant possible advantages compared to silicon. For cosmic ray stability, there are no unique results. Regarding thermal mechanical stress on interface materials, SiC is more challenging. The same may hold for electrical stress in passivation layers at the junction termination.     

Micro-CT-based identification of double porosity in fired clay ceramics

Optimizing thermal and mechanical properties of clay block masonry requires detailed knowledge on the microstructure of fired clays. We here identify the macro- and microporosity stemming from the use of three different pore-forming agents (expanded polystyrene, sawdust, and paper sludge) in different concentrations. Micro-CT measurements provided access to volume, shape, and orientation of macropores, and in combination with X-ray attenuation averaging and statistical analysis, also to voxel-specific microporosities. Finally, the sum of micro- and macroporosity was compared to corresponding data gained from two statistically and physically independent methods (namely from chemical analysis in combination with weighing, and from mercury intrusion porosimetry). Satisfactory agreement of all these independently gained experimental data renders our new concept for identifying the pore spaces of fired clay as a very promising tool supporting the further optimization of clay blocks.