Hierarchical development of training database for artificial neural network-based damage identification

Though serving as an effective means for damage identification, the capability of an artificial neural network (ANN) for quantitative prediction is substantially dependent on the amount of training data. In virtue of a concept of “Digital Damage Fingerprints” (DDF), a hierarchical approach for the development of training databases was proposed for ANN-based damage identification. With the object of exploiting the capability of ANN to address the key questions: “Is there damage?” and “Where is the damage?”, the amount of training data (damage cases) was increased progressively. Mutuality was established between the quantity of training data and the accuracy of answers to the two questions of interest, and was experimentally validated by identifying the position of actual damage in carbon fibre-reinforced composite laminates. The results demonstrate that such a hierarchical approach is capable of offering prediction as to the presence and location of damage individually, with substantially reduced computational cost and effort in the development of the ANN training database.

Hierarchical representation for spatial knowledge

One of the fundamental issues in building autonomous agents is to be able to sense, represent and react to the world. Some of the earlier work [Mor83, Elf90, AyF89] has aimed towards a reconstructionist approach, where a number of sensors are used to obtain input that is used to construct a model of the world that mirrors the real world. Sensing and sensor fusion was thus an important aspect of such work. Such approaches have had limited success, and some of the main problems were the issues of uncertainty arising from sensor error and errors that accumulated in metric, quantitative models. Recent research has therefore looked at different ways of examining the problems. Instead of attempting to get the most accurate and correct model of the world, these approaches look at qualitative models to represent the world, which maintain relative and significant aspects of the environment rather than all aspects of the world. The relevant aspects of the world that are retained are determined by the task at hand which in turn determines how to sense. That is, task directed or purposive sensing is used to build a qualitative model of the world, which though inaccurate and incomplete is sufficient to solve the problem at hand. This paper examines the issues of building up a hierarchical knowledge representation of the environment with limited sensor input that can be actively acquired by an agent capable of interacting with the environment. Different tasks require different aspects of the environment to be abstracted out. For example, low level tasks such as navigation require aspects of the environment that are related to layout and obstacle placement. For the agent to be able to reposition itself in an environment, significant features of spatial situations and their relative placement need to be kept. For the agent to reason about objects in space, for example to determine the position of one object relative to another, the representation needs to retain information on relative locations of start and finish of the objects, that is endpoints of objects on a grid. For the agent to be able to do high level planning, the agent may need only the relative position of the starting point and destination, and not the low level details of endpoints, visual clues and so on. This indicates that a hierarchical approach would be suitable, such that each level in the hierarchy is at a different level of abstraction, and thus suitable for a different task. At the lowest level, the representation contains low level details of agent's motion and visual clues to allow the agent to navigate and reposition itself. At the next level of abstraction the aspects of the representation allow the agent to perform spatial reasoning, and finally the highest level of abstraction in the representation can be used by the agent for high level planning.

The salt wedge position in a bar-blocked estuary subject to pulsed inflows

A series of laboratory experiments were carried out to investigate the response of a bar-blocked, saltwedge estuary to the imposition of both steady freshwater inflows and transient inflows that simulate storm events in the catchment area or the regular water releases from upstream reservoirs. The trapped salt water forms a wedge within the estuary, which migrates downstream under the influence of the freshwater inflow. The experiments show that the wedge migration occurs in two stages, namely (i) an initial phase characterized by intense shear-induced mixing at the nose of the wedge, followed by (ii) a relatively quiescent phase with significantly reduced mixing in which the wedge migrates more slowly downstream.

Provided that the transition time t_T between these two regimes satisfies t_T>g′h⁴L/q³α, as was the case for all our experiments and is likely to be the case for most estuaries, then the transition occurs at time t_T=1.2(gα³L⁶/g′³q²)^1/6, where g′=gΔρ/ρ0 is the reduced gravity, g the acceleration due to gravity, Δρ the density excess of the saline water over the density ρ₀ of the freshwater, q the river inflow rate per unit width, and L and α are the length and bottom slope of the estuary, respectively.

A simple model, based on conversion of the kinetic energy of the freshwater inflow into potential energy to mix the salt layer, was developed to predict the displacement xw over time t of the saltwedge nose from its initial position. For continuous inflows subject to t<t_T, the model predicts the saltwedge displacement as x_w/h=1.1 (t/τ)^1/3, where the normalizing length and time scales are h=(q²/g)^1/3 and τ=g′α²h4L/q³, respectively. For continuous inflows subject to t>tT, the model predicts the displacement as xw/h=0.45N1/6(t/τ)1/6/α, where N=q²/g′h²L is a non-dimensional number for the problem. This model shows very good agreement with the experiments. For repeated, pulsed discharges subject to t<t_T, the saltwedge displacement is given by (xw/h)3−(x0/h)(xw/h)2=1.3t/τ, where x₀ is the initial displacement following one discharge event but prior to the next event. For pulsed discharges subject to t>t_T, the displacement is given by (xw/h)⁶−(x0/h)(xw/h)⁵=0.008N(t/τ)/α⁶. This model shows very good agreement with the experiments for the initial discharge event but does systematically underestimate the wedge position for the subsequent pulses. However, the positional error is less than 15%.

Control loop for finding initial translator position of linear synchronous motor

This article presents a simple and reliable method for controlling the relative orientation between the two magnetic fields of a permanent magnet synchronous motor. Finding the initial (at motor powering- up time) value of this relative location is essential for the proper operation of the motor. After showing the system controllability, the utilized feedback control loop finds this initial relative orientation quickly and accurately. Further, using the proposed method allows considerable cost saving, as a transducer that is usually used for this purpose can be eliminated. The cost saving is most obvious in the case of linear motors and angle motors with large diameters. The way the problem is posed is an essential part of this work, and it is the reason behind the apparent simplicity of the solution. The method proposed relies on a single sensor, and it was tested when a relative encoder was used.

The position of Australian community sporting organisations in the third sector: membership profiles, characteristics and attitudes

Australian community sporting organisations have been relatively underresearched within the wider study of voluntary associations, yet their membership base is large and constitutes a sizable proportion of the population. This paper analyses data from the Australian Survey of Social Attitudes (AuSSA) 2003 (Gibson et al. 2004), initially to describe characteristics ofmembers ofcommunity sporting organisations in Australia (n=948). It goes on to compare attitudinal dimensions between members of sporting and other major third-sector organisations. On the basis of these comparisons three groupings of associations are suggested: social change, individual/social progress and individual/social maintenance. Sporting organisations form part of the latter category, and the paper briefly discusses the likely nature of social capital production associated with each.

Measuring Australia's well-being using hierarchical needs

A new approach to well-being measurement is presented in this paper based on multidimensional hierarchical human needs and motivation. This paper empirically applies this new measure of well-being to Australia for the period 1985–2000. This hierarchical approach is underpinned by a rigorous psychological theory of human motivation. Hierarchical human needs are classified into five categories. Eight indicators have been chosen to reflect these categories. A composite indicator of these eight indicators is calculated. This paper concludes that it is necessary to consider multidimensional human needs and motivation when analysing and seeking to improve well-being through economic and social development activities.

Phase behavior, crystallization, and hierarchical nanostructures in self-organized thermoset blends of epoxy resin and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymers

Nanostructured thermoset blends of bisphenol A-type epoxy resin (ER) and amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers were successfully prepared. Two samples of PEO-PPO-PEO triblock copolymer with different ethylene oxide (EO) contents, denoted as EO30 with 30 wt % EO content and EO80 with 80 wt % EO content, were used to form the self-organized thermoset blends of varying compositions using 4,4'-methylenedianiline (MDA) as curing agent. The phase behavior, crystallization, and morphology were investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). It was found that macroscopic phase separation took place in the MDA-cured ER/EO30 blends containing 60-80 wt % EO30 triblock copolymer. The MDA-cured ER/EO30 blends with EO30 content up to 50 wt % do not show macroscopic phase separation but exhibit nanostructures on the order of 10-30 nm as revealed by both the TEM and SAXS studies. The AFM study further shows that the ER/EO30 blend at some composition displays structural inhomogeneity at two different nanoscales and is hierarchically nanostructured. The spherical PPO domains with an average size of about 10 nm are uniformly dispersed in the 80/20 ER/EO30 blend; meanwhile, a structural inhomogeneity on the order of 50-200 nm is observed. The ER/EO80 blends are not macroscopically phase-separated over the entire composition range because of the much higher PEO content of the EO80 triblock copolymer. However, the ER/EO80 blends show composition-dependent nanostructures on the order of 10-100 nm. The 80/20 ER/EO80 blend displays hierarchical structures at two different nanoscales, i.e., a bicontinuous microphase structure on the order of about 100 nm and spherical domains of 10-20 nm in diameter uniformly dispersed in both the continuous microphases. The blends with 60 wt % and higher EO80 content are completely volume-filled with spherulites. Bundles of PEO lamellae with spacing of 20-30 nm interwoven with a microphase structure on the order of about 100 nm are revealed by AFM study for the 30/70 ER/EO80 blend.

What is the position/contribution of biology in environmental education

In this paper I intend to argue that biological science education and environmental education have traditionally represented fundamentally different discourses - that they have explicitly or implicitly adopted different epistemologies and ontologies - and that this difference has had implications for the conduct of research in these fields. I will draw on recent developments in theory, policy and practice in the field of environmental education to argue that this field tends to be located within a social discourse - that there is a foundation in policy and practice for considering environmental issues as fundamentally social and ethical in nature, rather than in some sense objectively existing. I then consider a rising topic in biology education (that of Biotechnology) as one which while tending to be treated within a scientific discourse, would be more fully explored educationally within a social discourse. I conclude by suggesting that in biology education research we need to consider a reconciliation of these historically differing perspectives.

Web page clustering : a hyperlink-based similarity and matrix-based hierarchical algorithms

This paper proposes a hyperlink-based web page similarity measurement and two matrix-based hierarchical web page clustering algorithms. The web page similarity measurement incorporates hyperlink transitivity and page importance within the concerned web page space. One clustering algorithm takes cluster overlapping into account, another one does not. These algorithxms do not require predefined similarity thresholds for clustering, and are independent of the page order. The primary evaluations show the effectiveness of the proposed algorithms in clustering improvement.

Marketing position taxonomies : an empirical analysis

Despite the continuing need for an empirically validated classification of marketing positions, for theoretical and practical purposes, it appears that no such schema exists. This study contributes to the development of such a taxonomy through an empirical examination of marketing positions. Specifically, the research extends an existing taxonomy by empirically investigating personal selling marketing activities. Based on the taxonomy developed by Darmon (1998), data were collected about the information load, information complexity, and time and relationship management activities of marketers. Various analytical techniques were used to investigate specific features of the instrument and the taxonomy, as well as to provide convergence for the conclusions drawn by the researchers. It was established that sales positions can be more meaningfully identified, and, therefore, better categorised, by six dimensions than by job title or job role. Further, it appears that marketers in the same selling position vary significantly on these dimensions. These findings have important implications for marketing theory, applied research and management. However, future research should refine the instrument used in this study, since some anomalies emerged in the findings, and extend the study by investigating a wider range of marketing positions. Such research may also explore whether the dimensions identified in this study influence the performance and job satisfaction of marketers, and the extent to which marketing managers account for these variations.

Interpersonal trust and formal controls in hierarchical relationships

This paper examines the influence of the level of interpersonal trust between superior and subordinate managers on the control behaviour of the former. On the basis of a questionnaire survey and interviews of senior managers from business organisations in Sri Lanka, and a survey of managers in Beijing-China the study explores the control behaviour of superior managers when their trust in a subordinate is high or low. Sri Lanka and China, societies in which the dependence on interpersonal trust is believed to be high, were chosen for the study to maximise the effect of interpersonal trust.

The findings of this study indicate that a superior’s high (low) trust in a subordinate is associated with a low (high) level of monitoring and a high (low) level of social interactions. The hypothesis that a superior’s high (low) level of trust is associated with a low (high) level of reliance on formal control was supported only in the Sri Lankan sample. These findings are at least indicative of control behaviour of superior managers in Sri Lanka and China and possibly of other countries in Asia. An understanding of the trust-sensitive control behaviour of managers in this region is particularly important for designing and implementing effective control systems for international organizations operating in the region.

On the effect of path loss rates on the optimal receiver position in sensor networks

In this paper we examine the problem of finding an optimal position for a receiver node in a single-hop sensor network. The basic idea is to minimize the network energy consumption according to a particular network cost function. Our contribution is to simply show the effect of signal path loss rates and sensor weighting on the optimal receiver position.

Adolescent home food environments and socioeconomic position

Many adolescents have diets that are less than optimal, particularly adolescents of low socioeconomic position (SEP). The determinants of SEP differences in adolescent dietary intake are poorly understood. This study examined the home food environments of adolescents and specifically investigated whether low SEP adolescents have less supportive home local environments, fewer eating rules and poorer home availability of fruit and vegetables than adolescents of high SEP. A cross-sectional, self-reported survey was administered to 3,264 adolescents in years 7 and 9, from 37 secondary schools in Victoria, Australia. Adolescent perceptions of the home meal environment, eating rules and home food availability were described and compared across SEP, which was measured using maternal education. Maternal education was linked to various aspects of the home meal environment, as well as home food availability, but not to eating rules. Low SEP adolescents were more likely to report that they were always allowed to watch television during meal times, and that unhealthy foods were always or usually available at home. In contrast, high SEP adolescents were more likely to report that vegetables were always served at dinner, that the evening meal was never an unpleasant time and always or usually a time for family connectedness, and that fruit was always or usually available at home. This study highlights aspects of the home food environment that might explain SEP variation in adolescent diets. Feasible ways of increasing home availability of healthy foods, and encouraging home meal environments to be supportive of healthy eating should be explored, particularly in households of low SEP adolescents.