Effective shear modulus approach for two dimensional solids and plate bending problems by meshless point collocation method

For the analysis of material nonlinearity, an effective shear modulus approach based on the strain control method is proposed in this paper by using point collocation method. Hencky’s total deformation theory is used to evaluate the effective shear modulus, Young’s modulus and Poisson’s ratio, which are treated as spatial field variables. These effective properties are obtained by the strain controlled projection method in an iterative manner. To evaluate the second order derivatives of shape function at the field point, the radial basis function (RBF) in the local support domain is used. Several numerical examples are presented to demonstrate the efficiency and accuracy of the proposed method and comparisons have been made with analytical solutions and the finite element method (ABAQUS).

How quantum theory is developing the field of information retrieval

This position paper provides an overview of work conducted and an outlook of future directions within the field of Information Retrieval (IR) that aims to develop novel models, methods and frameworks inspired by Quantum Theory (QT).

Quantum-like non-separability of concept combinations, emergent associates and abduction

Consider the concept combination ‘pet human’. In word association experiments, human subjects produce the associate ‘slave’ in relation to this combination. The striking aspect of this associate is that it is not produced as an associate of ‘pet’, or ‘human’ in isolation. In other words, the associate ‘slave’ seems to be emergent. Such emergent associations sometimes have a creative character and cognitive science is largely silent about how we produce them. Departing from a dimensional model of human conceptual space, this article will explore concept combinations, and will argue that emergent associations are a result of abductive reasoning within conceptual space, that is, below the symbolic level of cognition. A tensor-based approach is used to model concept combinations allowing such combinations to be formalized as interacting quantum systems. Free association norm data is used to motivate the underlying basis of the conceptual space. It is shown by analogy how some concept combinations may behave like quantum-entangled (non-separable) particles. Two methods of analysis were presented for empirically validating the presence of non-separable concept combinations in human cognition. One method is based on quantum theory and another based on comparing a joint (true theoretic) probability distribution with another distribution based on a separability assumption using a chi-square goodness-of-fit test. Although these methods were inconclusive in relation to an empirical study of bi-ambiguous concept combinations, avenues for further refinement of these methods are identified.

Change Point Estimation in Monitoring Survival Time

Precise identification of the time when a change in a hospital outcome has occurred enables clinical experts to search for a potential special cause more effectively. In this paper, we develop change point estimation methods for survival time of a clinical procedure in the presence of patient mix in a Bayesian framework. We apply Bayesian hierarchical models to formulate the change point where there exists a step change in the mean survival time of patients who underwent cardiac surgery. The data are right censored since the monitoring is conducted over a limited follow-up period. We capture the effect of risk factors prior to the surgery using a Weibull accelerated failure time regression model. Markov Chain Monte Carlo is used to obtain posterior distributions of the change point parameters including location and magnitude of changes and also corresponding probabilistic intervals and inferences. The performance of the Bayesian estimator is investigated through simulations and the result shows that precise estimates can be obtained when they are used in conjunction with the risk-adjusted survival time CUSUM control charts for different magnitude scenarios. The proposed estimator shows a better performance where a longer follow-up period, censoring time, is applied. In comparison with the alternative built-in CUSUM estimator, more accurate and precise estimates are obtained by the Bayesian estimator. These superiorities are enhanced when probability quantification, flexibility and generalizability of the Bayesian change point detection model are also considered.

A quantum information retrieval approach to memory

As computers approach the physical limits of information storable in memory, new methods will be needed to further improve information storage and retrieval. We propose a quantum inspired vector based approach, which offers a contextually dependent mapping from the subsymbolic to the symbolic representations of information. If implemented computationally, this approach would provide exceptionally high density of information storage, without the traditionally required physical increase in storage capacity. The approach is inspired by the structure of human memory and incorporates elements of Gardenfors’ Conceptual Space approach and Humphreys et al.’s matrix model of memory.

Non-compositional concepts and quantum tests

Compositionality is a frequently made assumption in linguistics, and yet many human subjects reveal highly non-compositional word associations when confronted with novel concept combinations. This article will show how a non-compositional account of concept combinations can be supplied by modelling them as interacting quantum systems.

New exact solutions for Hele-Shaw flow in doubly connected regions

Radial Hele-Shaw flows are treated analytically using conformal mapping techniques. The geometry of interest has a doubly-connected annular region of viscous fluid surrounding an inviscid bubble that is either expanding or contracting due to a pressure difference caused by injection or suction of the inviscid fluid. The zero-surface-tension problem is ill-posed for both bubble expansion and contraction, as both scenarios involve viscous fluid displacing inviscid fluid. Exact solutions are derived by tracking the location of singularities and critical points in the analytic continuation of the mapping function. We show that by treating the critical points, it is easy to observe finite-time blow-up, and the evolution equations may be written in exact form using complex residues. We present solutions that start with cusps on one interface and end with cusps on the other, as well as solutions that have the bubble contracting to a point. For the latter solutions, the bubble approaches an ellipse in shape at extinction.

Economic fluctuations and productivity in the Malaysian construction sector

Growth in productivity is the key determinant of the long-term health and prosperity of an economy. The construction industry being one of major strategic importance, its productivity performance has a significant effect on national economic growth. The relationship between construction output and economy has received intensive studies, but there is lack of empirical study on the relationship between construction productivity and economic fluctuations. Fluctuations in construction output are endemic in the industry. In part they are caused by the boom and slump of the economy as a whole and in part by the nature of the construction product. This research aims to uncover how the productivity of construction sector is influenced in the course of economic fluctuations in Malaysia. Malaysia has adopted three economic policies – New Economic Policy (1971-1990), National Development Policy (1991-2000) and the National Vision Policy (2001-2010) since gaining independence in 1959. The Privatisation Master Plan was introduced in 1991. Operating within this historical context, the Malaysian construction sector has experienced four business cycles since 1960. A mixed-method design approach is adopted in this study. Quantitative analysis was conducted on the published official statistics of the construction industry and the overall economy in Malaysia between 1970 and 2009. Qualitative study involved interviews with a purposive sample of 21 industrial participants. This study identified a 32-year long building cycle appears in 1975-2006. It is superimposed with three shorter construction business cycles in 1975-1987, 1987-1999 and 1999-2006. The correlations of Construction labour productivity (CLP) and GDP per capita are statistically significant for the 1975-2006 building cycle, 1987-1999 and 1999-2006 construction business cycles. It was not significant in 1975-1987 construction business cycles. The Construction Industry Surveys/Census over the period from 1996 to 2007 show that the average growth rate of total output per employee expanded but the added value per employee contracted which imply high cost of bought-in materials and services and inefficient usage of purchases. The construction labour productivity is peaked at 2004 although there is contraction of construction sector in 2004. The residential subsector performed relatively better than the other sub-sectors in most of the productivity indicators. Improvements are found in output per employee, value added per employee, labour competitiveness and capital investment but declines are recorded in value added content and capital productivity. The civil engineering construction is most productive in the labour productivity nevertheless relatively poorer in the capital productivity. The labour cost is more competitive in the larger size establishment. The added value per labour cost is higher in larger sized establishment attributed to efficient in utilization of capital. The interview with the industrial participant reveals that the productivity of the construction sector is influenced by the economic environment, the construction methods, contract arrangement, payment chain and regulatory policies. The fluctuations of construction demand have caused companies switched to defensive strategy during the economic downturn and to ensure short-term survival than to make a profit for the long-term survival and growth. It leads the company to take drastic measures to curb expenses, downsizing, employ contract employment, diversification and venture overseas market. There is no empirical evidence supports downsizing as a necessary step in a process of reviving productivity. The productivity does not correlate with size of firm. A relatively smaller and focused firm is more productive than the larger and diversified organisation. However diversified company experienced less fluctuation in both labour and capital productivity. In order to improve the productivity of the construction sector, it is necessary to remove the negatives and flaws from past practices. The recommended measures include long-term strategic planning and coordinated approaches of government agencies in planning of infrastructure development and to provide regulatory environments which encourage competition and facilitate productivity improvement.

Reaction to point and counterpoint : bold adventure or missed opportunity

The draft of the first stage of the national curriculum has now been published. Its final form to be presented in December 2010 should be the centrepiece of Labor’s Educational Revolution. All the other aspects – personal computers, new school buildings, rebates for uniforms and even the MySchool report card – are marginal to the prescription of what is to be taught and learnt in schools. The seven authors in this journal’s Point and Counterpoint (Curriculum Perspectives, 30(1) 2010, pp.53-74) raise a number of both large and small issues in education as a whole, and in science education more particularly. Two of them (Groves and McGarry) make brief reference to earlier attempts to achieve national curriculum in Australia. Those writing from New Zealand and USA will be unaware of just how ambitious this project is for Australia - a bold and overdue educational adventure or a foolish political decision destined to failure, as happened in the later 1970s and the 1990s.

The quantum inspired modelling of changing attitudes and self-organising societies

We utilise the well-developed quantum decision models known to the QI community to create a higher order social decision making model. A simple Agent Based Model (ABM) of a society of agents with changing attitudes towards a social issue is presented, where the private attitudes of individuals in the system are represented using a geometric structure inspired by quantum theory. We track the changing attitudes of the members of that society, and their resulting propensities to act, or not, in a given social context. A number of new issues surrounding this "scaling up" of quantum decision theories are discussed, as well as new directions and opportunities.

Nitrate reduction over nanoscale zero-valent iron prepared by hydrogen reduction of goethite

Nitrate reduction with nanoscale zero-valent iron (NZVI) was reported as a potential technology to remove nitrate from nitrate-contaminated water. In this paper, nitrate reduction with NZVI prepared by hydrogen reduction of natural goethite (NZVI-N, -N represents natural goethite) and hydrothermal goethite (NZVI-H, -H represents hydrothermal goethite) was conducted. Besides, the effects of reaction time, nitrate concentration, iron-to-nitrate ratio on nitrate removal rate over NZVI-H and NZVI-N were investigated. To prove their excellent nitrate reduction capacities, NZVI-N and NZVI-H were compared with ordinary zero-valent iron (OZVI-N) through the static experiments. Based on all above investigations, the mechanism of nitrate reduction with NZVI-N was proposed. The result showed that reaction time, nitrate concentration, iron-to-nitrate ratio played an important role in nitrate reduction by NZVI-N and NZVI-H. Compared with OZVI, NZVI-N and NZVI-H showed little relationship with pH. And NZVI-N for nitrate composition offers a higher stability than NZVI-H because of the existence of Al-substitution. Furthermore, NZVI-N, prepared by hydrogen reduction of goethite, has higher activity for nitrate reduction and the products contain hydrogen, nitrogen, NH 4 +, a little nitrite, but no NOx, meanwhile NZVI-N was oxidized to Fe 2+. It is a relatively easy and cost-effective method for nitrate removal, so NZVI-N reducing nitrate has a great potential application in nitrate removal of groundwater. © 2012 Elsevier B.V.

Coupling of energy from quantum emitters to the plasmonic mode of V groove waveguides: A numerical study

This work is a theoretical investigation into the coupling of a single excited quantum emitter to the plasmon mode of a V groove waveguide. The V groove waveguide consists of a triangular channel milled in gold and the emitter is modeled as a dipole emitter, and could represent a quantum dot, nitrogen vacancy in diamond, or similar. In this work the dependence of coupling efficiency of emitter to plasmon mode is determined for various geometrical parameters of the emitter-waveguide system. Using the finite element method, the effect on coupling efficiency of the emitter position and orientation, groove angle, groove depth, and tip radius, is studied in detail. We demonstrate that all parameters, with the exception of groove depth, have a significant impact on the attainable coupling efficiency. Understanding the effect of various geometrical parameters on the coupling between emitters and the plasmonic mode of the waveguide is essential for the design and optimization of quantum dot–V groove devices.

A novel quadratic Edge-based Smoothed Conforming Point Interpolation Method (ES-CPIM) for elasticity problems

his paper formulates an edge-based smoothed conforming point interpolation method (ES-CPIM) for solid mechanics using the triangular background cells. In the ES-CPIM, a technique for obtaining conforming PIM shape functions (CPIM) is used to create a continuous and piecewise quadratic displacement field over the whole problem domain. The smoothed strain field is then obtained through smoothing operation over each smoothing domain associated with edges of the triangular background cells. The generalized smoothed Galerkin weak form is then used to create the discretized system equations. Numerical studies have demonstrated that the ES-CPIM possesses the following good properties: (1) ES-CPIM creates conforming quadratic PIM shape functions, and can always pass the standard patch test; (2) ES-CPIM produces a quadratic displacement field without introducing any additional degrees of freedom; (3) The results of ES-CPIM are generally of very high accuracy.