Structural damage detection using frequency response functions and neural networks

This paper illustrates the damage identification and condition assessment of a three story bookshelf structure using a new frequency response functions (FRFs) based damage index and Artificial Neural Networks (ANNs). A major obstacle of using measured frequency response function data is a large size input variables to ANNs. This problem is overcome by applying a data reduction technique called principal component analysis (PCA). In the proposed procedure, ANNs with their powerful pattern recognition and classification ability were used to extract damage information such as damage locations and severities from measured FRFs. Therefore, simple neural network models are developed, trained by Back Propagation (BP), to associate the FRFs with the damage or undamaged locations and severity of the damage of the structure. Finally, the effectiveness of the proposed method is illustrated and validated by using the real data provided by the Los Alamos National Laboratory, USA. The illustrated results show that the PCA based artificial Neural Network method is suitable and effective for damage identification and condition assessment of building structures. In addition, it is clearly demonstrated that the accuracy of proposed damage detection method can also be improved by increasing number of baseline datasets and number of principal components of the baseline dataset.

Reducing Actuator Switchings for Motion Control of Autonomous Underwater Vehicles

A priority when designing control strategies for autonomous underwater vehicles is to emphasize their cost of implementation on a real vehicle. Indeed, due to the vehicles' design and the actuation modes usually under consideration for underwater plateforms the number of actuator switchings must be kept to a small value to insure feasibility and precision. This is the main objective of the algorithm presented in this paper. The theory is illustrated on two examples, one is a fully actuated underwater vehicle capable of motion in six-degrees-of freedom and one is minimally actuated with control motions in the vertical plane only.

Reducing actuator switchings for motion control of autonomous underwater vehicles

A priority when designing control strategies for autonomous underwater vehicles is to emphasize their cost of implementation on a real vehicle and at the same time to minimize a prescribed criterion such as time, energy, payload or combination of those. Indeed, the major issue is that due to the vehicles' design and the actuation modes usually under consideration for underwater platforms the number of actuator switchings must be kept to a small value to ensure feasibility and precision. This constraint is typically not verified by optimal trajectories which might not even be piecewise constants. Our goal is to provide a feasible trajectory that minimizes the number of switchings while maintaining some qualities of the desired trajectory, such as optimality with respect to a given criterion. The one-sided Lipschitz constant is used to derive theoretical estimates. The theory is illustrated on two examples, one is a fully actuated underwater vehicle capable of motion in six degrees-of-freedom and one is minimally actuated with control motions constrained to the vertical plane.

Engaging social customers : influencing new marketing strategies for social media information sources

A global, online quantitative study among 300 consumers of digital technology products found the most reliable information sources were friends, family or word of mouth (WOM) from someone they knew, followed by expert product reviews, and product reviews written by other consumers. The most unreliable information sources were advertising or infomercials, automated recommendations based on purchasing patterns or retailers. While a very small number of consumers evaluated products online, rating of products and online discussions were more frequent activities. The most popular social media websites for reviews were Facebook, Twitter, Amazon and e-Bay, indicating the importance of WOM in social networks and online media spaces that feature product reviews as it is the most persuasive piece of information in both online and offline social networks. These results suggest that ‘social customers’ must be considered as an integral part of a marketing strategy.

Newstead House : the social history, culture and architecture of a bygone era

Historic house museums form a significant component of the built heritage and social history of a country. They vary from the elaborate mansions of the wealthy to modest dwellings of the working class. Regardless of the original owner's status in society these house museums are vital to an understanding of architecture, culture and society from a bygone era. The Newstead House, the oldest surviving residence, in Brisbane, is the first house to be designated a 'Historic House Museum' in Queensland. It is a representative example of a house that demonstrates the British colonial heritage of 19th century Australia. Originally a modest cottage, on 34 acres of land, the Newstead house was built by a Scottish migrant. The ownership of the house and land changed many times, during the period from 1847 to 1939. During this period a series of prominent residents of Brisbane either owned or rented this residence. They included, an officer of the Royal Navy, politicians, magistrates, merchant ship owners, and a Consul General of the United States of America. As a result, the house went through a series of renovations and extensions to accommodate the needs of its owners and their position in society. This paper aims to investigate the significance of historic museum houses in educating the community on aspects of social history, culture and architecture of 19th century Australia. It will focus on the heritage listed Newstead House as a case study to demonstrate the significance of the house as an artefact and an educational tool.

Modeling the cumulative genetic risk for multiple sclerosis from genome-wide association data

Background: Multiple sclerosis (MS) is the most common cause of chronic neurologic disability beginning in early to middle adult life. Results from recent genome-wide association studies (GWAS) have substantially lengthened the list of disease loci and provide convincing evidence supporting a multifactorial and polygenic model of inheritance. Nevertheless, the knowledge of MS genetics remains incomplete, with many risk alleles still to be revealed. Methods: We used a discovery GWAS dataset (8,844 samples, 2,124 cases and 6,720 controls) and a multi-step logistic regression protocol to identify novel genetic associations. The emerging genetic profile included 350 independent markers and was used to calculate and estimate the cumulative genetic risk in an independent validation dataset (3,606 samples). Analysis of covariance (ANCOVA) was implemented to compare clinical characteristics of individuals with various degrees of genetic risk. Gene ontology and pathway enrichment analysis was done using the DAVID functional annotation tool, the GO Tree Machine, and the Pathway-Express profiling tool. Results: In the discovery dataset, the median cumulative genetic risk (P-Hat) was 0.903 and 0.007 in the case and control groups, respectively, together with 79.9% classification sensitivity and 95.8% specificity. The identified profile shows a significant enrichment of genes involved in the immune response, cell adhesion, cell communication/ signaling, nervous system development, and neuronal signaling, including ionotropic glutamate receptors, which have been implicated in the pathological mechanism driving neurodegeneration. In the validation dataset, the median cumulative genetic risk was 0.59 and 0.32 in the case and control groups, respectively, with classification sensitivity 62.3% and specificity 75.9%. No differences in disease progression or T2-lesion volumes were observed among four levels of predicted genetic risk groups (high, medium, low, misclassified). On the other hand, a significant difference (F = 2.75, P = 0.04) was detected for age of disease onset between the affected misclassified as controls (mean = 36 years) and the other three groups (high, 33.5 years; medium, 33.4 years; low, 33.1 years). Conclusions: The results are consistent with the polygenic model of inheritance. The cumulative genetic risk established using currently available genome-wide association data provides important insights into disease heterogeneity and completeness of current knowledge in MS genetics.

Integrating Intangible Cultural Heritage elements and learning strategy : a case study

Tanzania has a rich and diverse cultural history based on community cultural life. However, at present, young people have limited opportunity to exploit this richness of creative expressions and engage in creative jobs as their future career. Hence, the significant challenge remains: how to integrate Intangible cultural heritage elements and learning strategy as a means of promoting creative jobs for youth. This paper presents a case study on 'Strategies for youth employment in Tanzania: A creative industries approach'. The case study employed mixed methods incorporating questionnaires, interviews and focus groups and was held in Dar-Es-Salaam, Mwanza, Dodoma, Lindi and Morogoro from July to October, 2012. This paper discusses some of the issues and argues that there is no virtual utilization of the intangible cultural heritage knowledge and skills in 'putting education to work' (UNESCO, 2012) for the better prospects of youth. Although the discussion is specific to Tanzania, the case may also apply to other developing countries.

The pre-socialization of future journalists

While the role of university journalism education in the professionalization of journalists has been extensively debated, systematic and comparative studies of journalism students are still scarce. This paper reports the findings from a comparative study of journalism students in seven countries: Australia, Brazil, Chile, Mexico, Spain, Switzerland, and the United States. The data show a number of similarities, but also important differences between pre-professional cultures in journalism around the world. The findings are in line with recent conceptualizations of media systems, although some variations and particularities are observed at the country level. While students in all countries reject a loyal approach and favor a citizen-oriented role, they also do so to different extents. Brazilian and Chilean students believe in the citizen-oriented and watchdog roles, whereas their counterparts in Australia, Switzerland, and the United States favor the consumer-oriented approach to a greater extent. Mexican and Spanish students, on the other hand, while supporting the citizen-oriented role, reject the loyal role comparatively less than the rest of the countries.

A nonlinear observer for estimating transverse stability parameters of marine surface vessels

This paper presents a nonlinear observer for estimating parameters associated with the restoring term of a roll motion model of a marine vessel in longitudinal waves. Changes in restoring, also referred to as transverse stability, can be the result of changes in the vessel's centre of gravity due to, for example, water on deck and also in changes in the buoyancy triggered by variations in the water-plane area produced by longitudinal waves -- propagating along the fore-aft direction along the hull. These variations in the restoring can change dramatically the dynamics of the roll motion leading to dangerous resonance. Therefore, it is of interest to estimate and detect such changes.

Some Reflections on the Emergence of Multimodal Assemblages of Meaning

In this commentary I reflect upon the conceptualisation of human meaning-making, utilised in the two target articles, that relies heavily on speech as the main mode of semiosis and considers time only in its chronological form. Instead I argue that human existence is embodied and lived through multiple modalities, and involves not only sequential experience of time, but also experience of emergence. In order to move towards a conception of meaning-making that takes this into account, I introduce the social-semiotic theory of multimodality (Kress 2010) and discuss notions of ‘real duration’ (Bergson 1907/1998) and ‘lived time’ (Martin-Vallas 2009). I argue that dialogical (idiographic) researchers need to develop analytic and methodological tools that allow exploring the emergence of multimodal assemblages of meaning in addition to trying to avoid the monologisation of complex dynamic dialogical phenomena.