Interconversion of Prony series for relaxation and creep

Various algorithms have been proposed to solve the interconversion equation of linear viscoelasticity when Prony series are used for the relaxation and creep moduli, G(t) and J(t). With respect to a Prony series for G(t), the key step in recovering the corresponding Prony series for J(t) is the determination of the coefficients {jk} of terms in J(t). Here, the need to solve a poorly conditioned matrix equation for the {jk} is circumvented by deriving elementary and easily evaluated analytic formulae for the {jk} in terms of the derivative dG(s)/ds of the Laplace transform G(s) of G(t)

The creative engineering education imperative for twenty-First century living

Engineering and design in the twentieth century were conventionally taught from opposite ends of an educational spectrum. Engineering education built certainty on a strong foundation of fundamental knowledge, with students engaging with applications only once those fundamentals were ingrained. Design, in contrast, involved challenging certainty, with divergent thinking, experience mapping, problem framing and exploratory research. Over the last twenty years, elements of creativity and design process education have progressed into the majority of engineering curricula, but change is still slow. Yet, meanwhile, the pace of technological change impacting engineering futures and has been rapid. Arguably, the ability to be open and responsive to radical changes in thinking will become increasingly vital for engineering educators and practitioners with the unknowns of rapid change, both technical and social. For future engineering professionals to be able to be responsive to each wave of disruptive technology, engineering educators will have to re-invigorate their efforts in the adoption of pedagogy that supports creativity and innovation in order to keep pace. In addition, engineering graduates need to be educated not only in how to respond creatively to new technologies but in retaining the human-centred focus of development in an environment where rapid technological change has the possibility of fracturing or supporting human centred and community development. This paper proposes a return to education aimed at producing holistic engineers who integrate social aspirations and technological innovation into their work, as in the nineteenth century, to safeguard human development in the digital era of the twenty-first

Rethinking pedagogy for iterative design process learning and teaching

Product Design as an academic discipline is a relative newcomer to higher education. As a result it has had to adapt to the teaching practices and organisation already in place in Universities. However, with the viability of the current business model of higher education under threat from economic pressures, the dominance of established practice could conceivably be challenged, suggesting the time is right for a review of Product Design education as it operates within academia. Product Design educators need to focus on developing an innovative, practical approach to the organisation of learning based on sound design practice-based principles and provide leadership in pedagogy rather than adapting to the pedagogy of others. Design is a unique discipline that can impact on other disciplines as it is necessarily predicated on ideas of leadership and innovation. The role of Product Design in higher education should not deviate from that. Product Design has a real world heritage that is characterised by realistic, considered, innovative thinking. This paper is a reflective opinion piece, suggesting how that thinking could be applied to redress an imbalance in teaching design process to facilitate a more real world experience for the benefit of students and confidence in the discipline as a whole

Rheological implications of completely monotone fading memory

In the constitutive equation modeling of a (linear) viscoelastic material, the “fading memory” of the relaxation modulusG(t) is a fundamental concept that dates back to Boltzmann [Ann. Phys. Chem. 7, 624 (1876)]. There have been various proposals that range from the experimental and pragmatic to the theoretical about how fading memory should be defined. However, if, as is common in the rheological literature, one assumes that G(t) has the following relaxation spectrum representation: G(t)=∫₀∞ exp(−t/τ)[H(τ)/τ]dτ, t > 0, then it follows automatically that G(t) is a completely monotone function. Such functions have quite deep mathematical properties, that, in a rheological context, spawn interesting and novel implications. For example, because the set of completely monotone functions is closed under positive linear combinations and products, it follows that the dynamics of a linear viscoelastic material, under appropriate stress–strain stimuli, will involve a simultaneous mixture of different molecular interactions. In fact, it has been established experimentally, for both binary and polydisperse polymeric systems, that the dynamics can simultaneously involve a number of different molecular interactions such as the Rouse, double reptation and/or diffusion, [W. Thimm et al., J. Rheol., 44, 429 (2000); F. Léonardi et al., J. Rheol. 44, 675 (2000)]. The properties of completely monotone functions either yield new insight into modeling of the dynamics of real polymers, or they call into question some of the key assumptions on which the current modeling is based, such as the linearity of the Boltzmann model of viscoelasticity and/or the relaxation spectrum representation for the relaxation modulusG(t). If the validity of the relaxation spectrum representation is accepted, the resulting mathematical properties that follow from the complete monotonicity of G(t) allows one to place the classical relaxation model of Doi and Edwards [M. Doi and S. F. Edwards, J. Chem. Soc., Faraday Trans. 2 74, 1789 (1978)], as a linear combination of exp(−t/τ*) relaxation processes, each with a characteristic relaxation time τ*, on a more general and rigorous footing

Learning from Multiple Sources for Video Summarisation

Many visual surveillance tasks, e.g.video summarisation, is conventionally accomplished through analysing imagerybased features. Relying solely on visual cues for public surveillance video understanding is unreliable, since visual observations obtained from public space CCTV video data are often not sufficiently trustworthy and events of interest can be subtle. On the other hand, non-visual data sources such as weather reports and traffic sensory signals are readily accessible but are not explored jointly to complement visual data for video content analysis and summarisation. In this paper, we present a novel unsupervised framework to learn jointly from both visual and independently-drawn non-visual data sources for discovering meaningful latent structure of surveillance video data. In particular, we investigate ways to cope with discrepant dimension and representation whist associating these heterogeneous data sources, and derive effective mechanism to tolerate with missing and incomplete data from different sources. We show that the proposed multi-source learning framework not only achieves better video content clustering than state-of-the-art methods, but also is capable of accurately inferring missing non-visual semantics from previously unseen videos. In addition, a comprehensive user study is conducted to validate the quality of video summarisation generated using the proposed multi-source model

On the scaling of molecular weight distribution functionals

When formulating a constitutive equation model or a mixing rule for some synthetic or biological polymer, one is essentially solving an inverse problem. However, the data will not only include the results obtained from simple step strain, oscillatory shear, elongational, and other experiments, but also information about the molecular weight scaling of key rheological parameters (i.e., molecular weight distribution functionals) such as zero-shear viscosity, steady-state compliance, and the normal stress differences. In terms of incorporating such scaling information into the formulation of models, there is a need to understand the relationship between various models and their molecular weight scaling, since such information identifies the ways in which molecular weight scaling constrains the choice of possible models. In Anderssen and Mead (1998) it was established formally that the members of a quite general class of reptation mixing rules all had the same molecular weight scaling. The purpose of this paper is to first introduce the concept of a generalized reptation mixing rule, which greatly extends the class examined by Anderssen and Mead, and then show that all such rules have the same molecular weight scaling. The proof is similar to that given by Anderssen and Mead, but uses the implicit function theorem to establish the uniqueness of the mean values which arise when invoking various integral mean-value representations for the molecular weight distribution functionals considered. The rheological significance of the new generalized two-parameter mixing rule, proposed in this paper, is examined in some detail in the conclusions. In particular, it is used to established how one must construct a mixing rule for a general polydispersed polymer where the molecular dynamics involves some single, some double and some higher levels of multiple reptation. The work of Maier et al. (1998) and Thimm et al. (2000) is then utilized to illustrate and validate this proposal

Windfall Wealth and Shale Development in Appalachian Ohio: Preliminary Results

The response by agriculture/natural resources and community development Extension educators to shale development in Ohio has been proactive. There is a need, however, to understand the impact that shale development is having broadly on families and communities and specifically as it relates to lease payments and the perceptions and realities of resource windfalls or sudden wealth. This article presents the preliminary results of a qualitative study. In the course of data analysis, themes emerged around the topics of money, family and community life, and land. A discussion of the role of Extension professionals is provided

Direct Delivery of VP19 Double-Stranded RNA into Litopenaeus vannamei by Reverse Gavage Induces Protection against White Spot Syndrome Virus Disease

Double stranded RNA was synthesized in vitro and was delivered by reverse gavage (RG) compared to traditional intramuscular injection (IM) 3 days prior to challenge with a lethal dose of WSSV in both groups

Characterization of Newly Revealed Sequences in the Infectious Myonecrosis Virus Genome in \u3ci\u3eLitopenaeus vannamei\u3c/i\u3e

Infectious myonecrosis virus (IMNV) causes significant economic losses in farmed shrimp, where associated mortality in ponds can reach 70%. To explore host/pathogen interactions, a next-generation sequencing approach using lymphoid organ tissue from IMNV-infected Litopenaeus vannamei shrimp was conducted. Preliminary sequence assembly of just the virus showed that there were at least an additional 639 bp at the 5′ terminus and 23 nt at the 3′ terminus as compared with the original description of the IMNV genome (7561 nt). Northern blot and reverse transcription-PCR analysis confirmed the presence of novel sequence at both ends of the genome. Using 5′ RACE, an additional 4 nt were discovered; 3′ RACE confirmed the presence of 22 bp rather than 23 bp of sequence. Based on these data, the IMNV genome is 8226 bp in length. dsRNA was used to trigger RNA interference (RNAi) and suppress expression of the newly revealed genome sections at the 5′ end of the IMNV genome in IMNV-infected L. vannamei. An RNAi trigger targeting a 376 bp length of the 5′ UTR did not improve survival of infected shrimp. In contrast, an RNAi trigger targeting a 381 bp sequence in ORF1 improved survival to 82.2% as compared with 2.2% survival in positive control animals. These studies revealed the importance of the new genome sections to produce high-titre infection, and associated disease and mortality, in infected shrimp