http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12645 We develop technology to plan delivery routes for the supply of blood products to hospitals by a blood bank. The technology produces low cost, robust plans that hedge against the natural uncertainty associated with blood product usage at hospitals. The technology relies on sampling-based approaches involving integer programming and variable neighborhood search. An extensive computational study shows the efficacy of the two approaches and highlights the impact of product usage uncertainty on the resulting delivery plans. 2013-03-18T01:00:14.670Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12619 Branching variable selection can greatly affect the effectiveness and efficiency of a branch-and-bound algorithm. Traditional approaches to branching variable selection rely on estimating the effect of the candidate variables on the objective function. We propose an approach which is empowered by exploiting the information contained in a family of fathomed subproblems, collected beforehand from an incomplete branch-and-bound tree. In particular, we use this information to define new branching rules that reduce the risk of incurring inappropriate branchings. We provide computational results that demonstrate the effectiveness of the new branching rules on various benchmark instances. 2013-03-08T03:10:04.414Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12617 We introduce a problem faced by the blood bank of the Austrian Red Cross for Eastern Austria: how to cost-effectively organize the delivery of blood products to Austrian hospitals? We investigate the potential value of switching from the current vendee-managed inventory set up to a vendor-managed inventory system. We present solution approaches based on integer programming and variable neighborhood search and evaluate their performance. 2013-03-08T01:10:05.322Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12595 Companies in the concrete industry are facing the following scheduling problem on a daily basis: concrete produced at several plants has to be delivered at customers’ construction sites using a heterogeneous fleet of vehicles in a timely, but cost-effective manner. As the ordered quantity of concrete typically exceeds the capacity of a single vehicle several deliveries need to be scheduled in order to fulfill an order. The deliveries cannot overlap and the time between consecutive deliveries has to be small. Our solution approach effectively integrates optimization and heuristic techniques. Information is passed back and forth between an integer multicommodity flow optimization component and a variable neighborhood search component in order to find high-quality solutions in a reasonable amount of time. Even though both components are capable of producing feasible solutions, the integrated approach is far more effective. Computational results show that our hybrid approach outperforms an innovative metaheuristic approach by more than 6% on average for large instances. 2013-03-06T00:30:05.170Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:11910 Around 1828, T. Clausen discovered that the square of certain hypergeometric ₂F₁ function can be expressed as a hypergeometric ₃F₂ function. Special cases of Clausen’s identities were later used by S. Ramanujan in his derivation of 17 series for 1/π. Since then, there were several attempts to find new analogues of Clausen’s identities with the hope to derive new classes of series for 1/π. Unfortunately, none were successful. In this article, we will present three new analogues of Clausen’s identities. Their discovery is motivated by the study of relations between modular forms of weight 2 and modular functions associated with modular groups of genus 0. 2012-11-02T02:41:00.230Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1842 The theory of fundamental design limitations is well understood for the case that the performance variable is measured for feedback. In the present paper, we extend the theory to systems for which the performance variable is not measured. We consider only the special case for which the performance and measured outputs and the control and exogenous inputs are all scalar signals. The results of the paper depend on the control architecture, specifically, on the location of the sensor relative to the performance output, and the actuator relative to the exogenous input. We show that there may exist a tradeoff between disturbance attenuation and stability robustness that is in addition to the tradeoffs that exist when the performance output is measured. We also develop a set of interpolation constraints that must be satisfied by the disturbance response at certain closed right half plane poles and zeros, and translate these constraints into generalizations of the Bode and Poisson sensitivity integrals. In the absence of problematic interpolation constraints we show that there exists a stabilizing control law that achieves arbitrarily small disturbance response. Depending on the system architecture, this control law will either be high gain feedback or a finite gain controller that depends explicitly on the plant model. We illustrate the results of this paper with the problem of active noise control in an acoustic duct. 2012-10-08T00:00:05.845Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1551 Brushless doubly fed induction machines (BDFIMs) have been extensively researched over because of the possibility of using a partially rated inverter in many applications with limited speed variations. However, the special cage rotor construction and substantial rotor losses is one of the key deficiencies of these machines. A similar and extremely interesting machine, the brushless doubly fed reluctance machine (BDFRM), has been largely ignored in comparison. This was mainly due to the fact that reluctance rotor designs were not capable of generating saliency ratios large enough to make the BDFRM competitive with other machines. However, developments in reluctance rotors, spurred on by research into synchronous reluctance machines, have resulted in high-saliency-ratio cageless rotors that are economical to build. This, together with the promise of higher efficiency and simpler control compared to the BDFIM, means that further investigation of the BDFRM is warranted. This paper presents a comparative theoretical analysis and aspects of practical implementation of the important control strategies and associated machine performance/inverter size tradeoffs for the BDFRM in the light of its most likely applications-large-pump-type adjustable-speed drives and variable-speed constant-frequency wind power generation systems. 2012-10-07T23:20:03.252Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8687 This paper examines the effect of cell loadings on the performance of a group based multicast algorithm implemented on the HSDPA air interface. The group based multicast scheme could offer higher QoS and capacity in a HSDPA network. However, the performance of the multicast algorithm could be affected by neighboring cell loadings. In order to compensate the variable SINR conditions caused by the variation in neighboring cell loading it is necessary to optimize the group switching algorithm to maintain high QoS in a cell and to minimize the uplink feedback traffic. The paper presents simulation results showing the effects of cell loading on the performance of the group based multicasting scheme. An OPNET based multi-cell simulation model has been used to obtain the results. 2012-06-05T01:31:05.223Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6956 Metazoan cells harness the power of actin dynamics to create cytoskeletal arrays that stimulate protrusions and drive intracellular organelle movements. In plant cells, the actin cytoskeleton is understood to participate in cell elongation; however, a detailed description and molecular mechanism(s) underpinning filament nucleation, growth, and turnover are lacking. Here, we use variable-angle epifluorescence microscopy (VAEM) to examine the organization and dynamics of the cortical cytoskeleton in growing and nongrowing epidermal cells. One population of filaments in the cortical array, which most likely represent single actin filaments, is randomly oriented and highly dynamic. These filaments grow at rates of 1.7 μm/s, but are generally short-lived. Instead of depolymerization at their ends, actin filaments are disassemble by severing activity. Remodeling of the cortical actin array also features filament buckling and straightening events. These observations indicate a mechanism inconsistent with treadmilling. Instead, cortical actin filament dynamics resemble the stochastic dynamics of an in vitro biomimetic system for actin assembly. 2012-01-30T05:04:36.282Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:6056 Natural Field Orientation (NFO) Control proposed in the 1980psilas is an alternative low cost control method for induction machines. The NFO Control has shown to have some stability issues in regeneration which have been partially addressed in the previous papers. In the present paper a linearised stability analysis is presented for the motor/drive system based on both the non-augmented and the augmented versions of the NFO control. Based on the results of this analysis, the limitations of the augmentation strategy are explored and conditions are identified when it does not ensure stability. Theoretical results are confirmed by simulations and experiments. Directions of further improvement of the NFO stability are outlined. 2012-01-30T04:06:08.865Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:8784 The aim of this paper is to detect fraud in telecommunications data which consists of millions of call records generated each day. The fraud detection is implemented via the construction of user call profiles using the calls detail records (CDR) data. This paper attempts to investigate the reliability of the unsupervised Random Forest method in building the profiles using its variable importance measure. Four different simulation scenarios, using different number of variable selection in each node of the tree, are performed. 2011-08-30T04:50:03.839Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:7134 A procedure, formulated in the space of the load processes, is described for estimating the reliability of structures subject to multi-parameter time-varying loading. For most realistic reliability problems the load process space is of low order. As a result, the required multidimensional integration is significantly simplified. The proposed approach also has well defined steps. As a result, there is increased transparency and reduced problems of integration instability and non-convergence. Both loads and resistances are described in terms of random variable parameters and time dependent structural resistances can be considered. Numerical examples are given to illustrate the proposed method. Example applications are given for a fixed base rigid-plastic portal frame subjected to time dependent loads and resistances. Linear and non-linear limit state equations and Normal and non-Normal distribution of the random variables are considered and compared, in some cases, to the results evaluated using Monte Carlo simulation. 2011-02-02T23:10:06.952Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:4333 An individual-based model which produces nonlinear predator-prey dynamics is described. The importance of individual variation to the stability of the population dynamics predicted by the model and the advantages of the individual-based approach to modelling ecological systems is discussed. The individual-based model is compared with the traditional approach of population ecology - the modelling of populations with state variable equations. The individual-based model built here produces similar patterns of mutual dependence of the populations to those produced by the state variable model but has additional utility. It greatly simplifes the adjustment of individual environmental parameters which may be built into the model and it makes it possible to follow individuals or individual parameter values through the simulation. The cost of the utility of the individual-based approach is in the complexity of the model itself, which is more difficult to build than many state variable models. A common finding in the literature of individual-based modelling in ecology is the importance of individual variation. The individual-based model described here is built with a minimum of biological complexity, but still we nd that individual variation in the model has profound effects on the stability of the population levels over long time periods. 2010-09-27T02:30:01.649Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2592 A comprehensive comparative study of various vector control strategies for the brushless doubly fed reluctance machine (BDFRM) is presented in this paper. Open and closed-loop scalar control algorithms for the machine are developed and examined by computer simulations. Particular emphasis is placed on the machine performance/inverter size trade-offs associated with the control properties considered. Most of this analysis is carried out using normalised modelling techniques specifically focusing on the BDFRM target applications-large pump-type drives and variable speed constant frequency wind-turbine generators. 2010-04-27T06:59:38.269Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2504 This paper presents the design of an induction machine current controller that is entirely implemented in digital hardware. A hardware current controller allows high switching frequencies with only modest processing power, as well as simplified controller hardware and software. The paper briefly presents the concepts of the algorithm implemented, and then outlines the changes that are made to make the digital implementation even more efficient. It then discusses the architecture used for the hardware design. Experimental results are presented to demonstrate the algorithm's performance 2010-04-27T06:49:56.510Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3009 There are a number of diseases where the 5-α-reductase (5AR) enzyme is of therapeutic interest as a drug target. Currently the crystal structure for 5-α-reductase is unavailable, thus ligand-based pharmacophore techniques are beneficial in the drug development process. We have developed pharmacophores to aid inhibitor design for both human types I (preliminary) and II 5-α-reductase isozymes and also the rat type II isozyme. To our knowledge, these are the first published pharmacophores for inhibitors of the human type I and rat type II enzymes. A comparison between isozymes and the previously published human type II isozyme pharmacophore is also presented. 2010-04-27T06:47:09.459Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:966 In this paper, the large sample properties of the separable nonlinear least squares algorithm are investigated. Unlike the previous results in the literature, the data are assumed to be complex valued, and the whiteness assumption on the measurement noise sequence has been relaxed. Convergence properties of the parameter estimates are established. Asymptotic accuracy analysis has been carried out, in which the assumptions used are relatively weaker than the assumptions in the previous related works. It is shown under quite general conditions that the parameter estimates are asymptotically circular. Conditions for asymptotic complex normality are also established. Next, a bound on the deviation of the asymptotic covariance matrix from the Crame/spl acute/r-Rao bound (CRB) is derived. Finally, a sufficient condition for the nonlinear least squares estimate to achieve the Crame/spl acute/r-Rao lower bound is established. The results presented in this paper are general and can be applied to any specific application where separable nonlinear least squares is employed. 2010-04-27T06:40:44.748Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1228 Background: Underground coal-mine workers suffer noise-induced hearing loss and continue working in the industry while having varying degrees of deafness. Few studies have researched the risk to safety arising from the loss of hearing. Aims: This study is designed to investigate the possible association between hearing loss and accidents in the New South Wales underground coal-mining industry. Methods: A study was conducted, gathering data over a 10-year period from 1994 to 2003, which identified 97 cases that have had accidents and 983 controls that have had no accidents. Hearing loss levels were noted and compared in the cases and controls. Multiple logistic regression was used to determine whether the variables were significant risk factors in the occurrence of accidents. Results: Hearing loss levels in the total cohort varied from 0 to 54%. The proportion of cases with hearing loss appeared to be significantly higher in the young age group of <29 years than in the controls, but was not significantly different in the older age groups. Conclusions: This study indicates that workers who have lost up to 54% binaural high tone hearing and are older than 29 years do not appear to have an increased risk to safety when compared with workers who do not have hearing loss. However, workers in the young age group of <29 years who have high tone hearing loss may be at an increased risk of accident. 2010-04-27T06:39:17.809Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1136 This paper presents a constitutive formulation for materials with strain gradient effects by internal-variable approach with normality structure. Specific micro-structural rearrangements are assumed to account for the inelasticity deformations for this class of materials, and enter the constitutive formulations in form of internal variables. It is further assumed that the kinetic evolution of any specific micro-structural rearrangement may be fully determined by the thermodynamic forces associated with that micro-structural rearrangement, by normality relations via a flow potential. Macroscopic gradient-enhanced inelastic behaviours may then be predicted in terms of the microscopic internal variables and their conjugate forces, and thus a micro–macro bridging formulation is available for strain-gradient-characterised materials. The obtained formulations are first applied to crystallographic materials, and a crystal gradient plasticity model is developed to account for the influence of microscopic slip rearrangements on the macroscopic gradient-dependent mechanical behaviour for this class of materials. Micro-cracked geomaterials are also treated with these formulations and a gradient-enhanced damage constitutive model is developed to address the impacts of the evolutions of micro-cracks on the macroscopic inelastic deformations with strain gradient effects for these materials. The available formulations are further compared with other thermodynamic approaches of constitutive developing. 2010-04-27T06:05:32.680Z ]]>