Damage identification scheme based on compressive sensing

Civil infrastructures are critical to every nation, due to their substantial investment, long service period, and enormous negative impacts after failure. However, they inevitably deteriorate during their service lives. Therefore, methods capable of assessing conditions and identifying damage in a structure timely and accurately have drawn increasing attention. Recently, compressive sensing (CS), a significant breakthrough in signal processing, has been proposed to capture and represent compressible signals at a rate significantly below the traditional Nyquist rate. Due to its sound theoretical background and notable influence, this methodology has been successfully applied in many research areas. In order to explore its application in structural damage identification, a new CS-based damage identification scheme is proposed in this paper, by regarding damage identification problems as pattern classification problems. The time domain structural responses are transferred to the frequency domain as sparse representation, and then the numerical simulated data under various damage scenarios will be used to train a feature matrix as input information. This matrix can be used for damage identification through an optimization process. This will be one of the first few applications of this advanced technique to structural engineering areas. In order to demonstrate its effectiveness, numerical simulation results on a complex pipe soil interaction model are used to train the parameters and then to identify the simulated pipe degradation damage and free-spanning damage. To further demonstrate the method, vibration tests of a steel pipe laid on the ground are carried out. The measured acceleration time histories are used for damage identification. Both numerical and experimental verification results confirm that the proposed damage identification scheme will be a promising tool for structural health monitoring.

A kinematics study of variable lead axisymmetric forward spiral extrusion

Variable lead axi-symmetric forward spiral extrusion (VLAFSE) allows far more efficient strain accumulation than constant lead counterpart AFSE. It eliminates the rigid body rotation of the sample in an AFSE die which only causes frictional loss and has no contribution to the deformation. Based on a proposed velocity field, the kinematic formulation for VLAFSE is presented, utilized to predict strain components in the deformation zone and compared with experimental measurements. A simple closed form solution of the VLAFSE problem is presented which describes the flow of material inside the extrusion die. The results confirm that the effective strain of the process accumulates non-linearly in the both radial and extrusion directions.

The effect of low parental warmth and low monitoring on disordered eating in mid-adolescence: findings from the Australian Temperament Project

OBJECTIVE: To investigate the interactions between low parental warmth and monitoring at age 13-14 years and disordered eating attitudes and behaviours at age 15-16 years. METHOD: Data on 1300 (667 females) adolescents and their parents were drawn from The Australian Temperament Project (ATP), a 30 year (15 wave) population based longitudinal study of social-emotional development. Parent participants completed surveys on parenting practices in late childhood, and adolescent participants reported disordered eating using the drive for thinness and bulimia subscales of the Eating Disorder Inventory (EDI) and an additional body dissatisfaction scale. Interaction was examined on the additive scale by estimating super-additive risk; i.e., risk in excess of the sum of individual risks. RESULTS: For boys, neither parental warmth or monitoring, nor their interaction, was related to disordered eating. For girls, low parental warmth (alone) was associated with bulimic behaviours. In contrast, exposure to both low monitoring and warmth was associated with ∼3½-fold, ∼4-fold and ∼5-fold increases in the odds of reporting body dissatisfaction, drive for thinness and bulimia, respectively. For body dissatisfaction and drive for thinness, risk associated with joint exposure exceeded the sum of individual risks, suggesting an additive interaction between parenting styles. CONCLUSION: Further investment in family-level interventions that focus on promoting parental monitoring behaviour and a warm parent-child relationship remain important strategies for preventing a range of disordered eating behaviours in adolescents.

Do we challenge students enough? Model Solar vehicle project challenges potential engineers.

A major challenge to Australia and New Zealand is the perceived need to develop "knowledge economies" based on the expertise of university graduates,  especially engineers. However, many countries are finding less students are choosing to study engineering. At the same time, there is increasing concern about increased levels of greenhouse gases leading to global warming with species loss, rising sea levels and desertification being likely outcomes. Numerous competitions have been established aimed at attracting school students into science and engineering careers. Environmental groups have also sponsored educational activities to increase student awareness of alternative energy technologies. One activity which provides both a science and engineering challenge while also raising awareness of alternative energy and more efficient conversion of that energy for transport is the Model Solar Vehicle Challenge (MSVC). The Challenge, which provides a solar powered boat competition for younger students and a car race for the older ones, has involved thousands of Victorian school students since 1990 and students from all Australian states since 1993. Boats race in 2 or 3 lanes guided by an overhead wire in a 10 metre pool, and cars race 100 metres around a figure 8 track. Top boats average over 7 kph and cars reach speeds of 25 kph at the finish line. This paper will discuss the conduct of the Challenge, motivation of participants, the depth of learning which can be achieved and the effectiveness of the Challenge in encouraging students to continue with science subjects through school and to select engineering at university. It will also briefly discuss the lessons that can be learnt from the MSVC and applied to first year university courses.

A biopsychosocial model for understanding body image and body change strategies among children

The present study was designed to assess the role of biopsychosocial factors in understanding body image concerns and cognitions and behaviors related to losing weight or increasing muscles among 507 children (270 girls and 237 boys) aged between 8 and 11 years. Biological, psychological, and sociocultural factors have been found to be relevant in understanding the development of body image concerns and weight loss strategies among children. However, these factors have not been examined together in a single study; thus, the relative influence of each factors and how these factors may interact is not known. In the current study, body mass index (BMI) was found to be a good indicator of girls' and boys' body dissatisfaction, while the main indicator of children's body change strategies was perceived pressure from parents, peers, and the media. Overall, there were more similarities than differences between girls and boys. The age between 8 and 11 years is a significant period to commence studying body image concerns and body change strategies, as it can be used to help us understand the emergence of gender differences in children's weight and muscle concerns.

A field test of the diversity-openness moderator model in newly formed groups: openness to diversity affects group decision effectiveness and interaction patterns

Detrimental effects of diversity in workgroups has frequently been observed but research identifying the factors that lead to negative or positive effects in heterogeneous groups is lacking. The perceived dissimilarity openness moderator model provides one explanation of the process by which diversity influences group affective, behavioral, and cognitive outcomes. Specifically the model identifies individual, group, and organizational openness as moderating the effects of diversity in workgroups. In this paper evidence is provided from a field study that increased openness to perceived dissimilarity leads to better outcomes in newly formed groups. This study also constitutes a significant building block toward the development of theory concerning the moderating variables of the relationship between diversity and group processes, and outcomes of organizations.

An intelligent energy management model for a parallel hybrid vehicle under combined loads

To exploit the benefits offered by parallel HEVs, an intelligent energy management model is developed and evaluated in this paper. Despite most existing works, the developed model incorporates combined wind/drag, slope, rolling, and accessories loads to minimise the fuel consumption under varying driving conditions. A slope prediction unit is also employed. The engine and the electric motor can output power simultaneously under a heavy-load or a slopped road condition. Two simulation were conducted namely slopped-windy-prediction and slopped-windy-prediction-hybrid. The results indicate that the vehicle speed and acceleration is smoother where the hybrid component was included. The average fuel consumption for the first and second simulations were 7.94 and 7.46 liter/100 km, respectively.

Examination of a multi-factorial model of body-related experiences during pregnancy : the relationships among physical symptoms, sleep quality, depression, self-esteem, and negative body attitudes

The aim of this cross-sectional study was to investigate relationships among women's body attitudes, physical symptoms, self-esteem, depression, and sleep quality during pregnancy. Pregnant women (N = 215) at 15–25 weeks gestation completed a questionnaire including four body image subscales assessing self-reported feeling fat, attractiveness, strength/fitness, and salience of weight and shape. Women reported on 29 pregnancy-related physical complaints, and completed the Beck Depression Inventory, Rosenberg Self-esteem Scale, and Pittsburgh Sleep Quality Index. In regressions, controlling for retrospective reports of body image, more frequent and intense physical symptoms were related to viewing the self as less strong/fit, and to poorer sleep quality and more depressive symptoms. In a multi-factorial model extending previous research, paths were found from sleep quality to depressive symptoms to self-esteem; self-esteem was found to be a mediator associated with lower scores on feeling fat and salience of weight and shape, and on higher perceived attractiveness.

Customer-product interaction : a model for new product development in entrepreneurial firms

Use of New Product Development (NPD) methods may benefit New Zealand SMEs and entrepreneurial firms in gaining greater market share. In this paper we review the literature on New Product Development, NPD theory and methods for early stage product design and development. Our reading suggests that product design has greater success when the customer is involved in the design effort. It also recommends methods of approach to new markets in the (NPD) life cycle. The literature further elucidates methods for identification of product design criteria based on customer needs identification. In essence, customer-product interaction in the early stages of product development is important to product success in new markets for entrepreneurial firms and SMEs. Of particular interest are early-stage NPD research methods and their influence on the company’s marketing strategy.

What decision rules might pink-footed geese use to depart on migration? An individual-based model

Decisions taken during migration can have a large effect on the fitness of birds. Migration must be accurately timed with food availability to allow efficient fueling but is also constrained by the optimal arrival date at the breeding site. The decision of when to leave a site can be driven by energetics (sufficient body stores to fuel flight), time-related cues (internal clock under photoperiodic control), or external cues (temperature, food resources). An individual based model (IBM) that allows a mechanistic description of a range of departure decision rules was applied to the spring migration of pink-footed geese (Anser brachyrhynchus) from wintering grounds in Denmark to breeding grounds on Svalbard via 2 Norwegian staging sites. By comparing predicted with observed departure dates, we tested 7 decision rules. The most accurate predictions were obtained from a decision rule based on a combination of cues including the amount of body stores, date, and plant phenology. Decision rules changed over the course of migration with the external cue decreasing in importance and the time-related cue increasing in importance for sites closer to breeding grounds. These results are in accordance with descriptions of goose migration, following the “green-wave”: Geese track the onset of plant growth as it moves northward in spring, with an uncoupling toward the end of the migration if time is running out. We demonstrate the potential of IBMs to study the possible mechanisms underlying stopover ecology in migratory birds and to serve as tools to predict consequences of environmental change.