bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptive neuro-fuzzy inference system-based controllers for smart material actuator modelling
Authors: Grigorie T L , Botez R M
Published: June 2009

An intelligent approach for smart material actuator modelling of the actuation lines in a morphing wing system is presented, based on adaptive neuro-fuzzy inference systems. Four independent neuro-fuzzy controllers are created from the experimental data using a hybrid method — a combination of back propagation and least-mean-square methods — to train the fuzzy inference systems. The controllers' objective is to correlate each set of forces and electrical currents applied on the smart material actuator to the actuator's elongation. The actuator experi-mental testing is performed for five force cases, using a variable electrical current. An integrated controller is created from four neuro-fuzzy controllers, developed with Matlab/Simulink software for electrical current increases, constant electrical current, electrical current decreases, and for null electrical current in the cooling phase of the actuator, and is then validated by comparison with the experimentally obtained data.
Path-tracking controller design and implementation of a vision-based wheeled mobile robot
Authors: Yang J-L , Su D-T , Shiao Y-S , Chang K-Y
Published: June 2009

This paper presents techniques for building system configuration, control architecture, and implementation of a vision-based wheeled mobile robot (WMR). The completed WMR has been built with the dead-reckoning method so as to determine the vehicle's velocity and posture by the numerical differentiation/integration over short travelling. The developed proportional-integral-derivative (PID) controllers show good transient performances; that is, the velocity of right and left wheels can track the commands quickly and correctly. Moreover, the path-tracking control laws have also been executed within the digital signal processor (DSP)-based controller in the WMR. The image-recognized system can obtain motion information at 15 frames/s by using the hybrid intelligent system (HIS) model, which is one of the well-known colour detection methods. The better performance a vision system has, the more successful the control laws design. The WMR obtains its posture from the dead-reckoning device together with the vision system. These subsystems are integrated, and the operators of the whole system are completed. This WMR system can be thought of as a platform for testing various tracking control laws and a signal-filtering method. To solve the problem of position/orientation tracking control of the WMR, two kinematical optimal non-linear predictive control laws are developed to manipulate the vehicle to follow the desired trajectories asymptotically. A Kalman filter scheme is used to reduce the bad effect of the imagine nose; thereby the accuracy of pose estimation can be improved. The experimental system is composed of a wireless RS232 modem, a DSP-based controller for the WMR, and a vision system with a host computer. A computation-effective and high-performance DSP-based controller is constructed for executing the developed sophisticated path-tracking laws. Finally, the simulation and experimental results show the feasibility and effectiveness of the proposed control laws.
Non-linear friction compensation using backstepping control and robust friction state observer with recurrent fuzzy neural networks
Authors: Kim B S , Han S I
Published: June 2009

A robust precise tracking control for a servomechanical system with non-linear dynamic friction is presented. The LuGre friction that is adopted as a non-linear friction model contains both a directly immeasurable friction state variable and the uncertainty caused by incomplete parameter identification and change of the condition of contact surface. To provide an efficient solution to these problems, a composite robust control scheme is proposed, which consists of a robust friction state observer, a recurrent fuzzy neural network (RFNN) approximator, and an adaptive reconstructed error compensator with backstepping control. A robust friction state observer is designed to estimate the unknown internal state of the LuGre friction model. Next, a proposed RFNN scheme approximates the lumped friction torque uncertainty. Finally, an adaptive error compensator eliminates a reconstructed error arising from RFNN approximation. Some simulations and experiments for a ball-screw servosystem are carried out to demonstrate the performance of a proposed control scheme.
Filtering controller in sliding mode: From the estimation to control
Authors: Wang S , Burton R , Habibi S
Published: June 2009

The paper introduces the concept of a filtering controller (FC), which uses sliding mode control as its basis. The FC ‘seamlessly’ integrates a smoothed variable structure filter with a variable structure controller. The paper provides the conceptual derivations of variable structure filtering and its integration with a controller in the presence of uncertainties and non-linearities in control systems. Concepts supported with basic describing equations are used to demonstrate how the FC is developed.
Atomistic simulation of nanoindentation of iron with different indenter shapes
Authors: Lu C , Gao Y , Michal G , Huynh N N , Zhu H T , Tieu A K
Published: June 2009

In this article molecular dynamics (MD) simulations have been conducted to investigate the effect of the indenter shape on the nanoindentation behaviours of iron with body centred cubic structure. Two types of indenters (hemispherical indenter and pyramidal indenter) with dimensions of several nanometres have been modelled. The simulation results have shown that the indenter shape significantly influences the nanoindentation behaviours at such small scale. The indentation force increases with indentation depth during loading for the hemispheri-cal indenter, while the indentation force is low in values for the pyramidal indenter. To validate the MD model nanoindentation experiments have been carried out. The calculated indentation hardness of the hemispherical indenter is in reasonable agreement with the experimental value.
Development and preliminary performance evaluation of discontinuous fibre reinforced thermoplastic leaf spring
Authors: Subramanian C , Senthilvelan S
Published: June 2009

Leaf spring plays a significant role in the riding comfort of an automobile. Thermoplastic composite materials are replacing many metallic parts in an automobile system. The main objective of the present work is to identify the scope of thermoplastic composite material for leaf spring application. Emphasis is given to understand the effect of reinforced fibre length on the leaf spring performance. In all, 20 per cent discontinuous long and short glass fibre reinforced polypropylene (PP) materials were considered for the development. Prior to the development and evaluation of leaf springs, the influence of reinforced fibre length over leaf spring material behaviour has been investigated. With the increase in reinforced fibre length, crystallinity of the base matrix structure, thermal characteristics, and mechanical behaviour under static and dynamic loading conditions were found to be improved. Mono, discontinuous fibre reinforced thermoplastic leaf spring of varying width is designed and injection molded. A servo-hydraulic fatigue testing facility coupled with linear guide ways is utilized to evaluate the preliminary leaf spring performance parameters, namely load deflection, strain rate sensitivity, hysteresis, and damping behaviour. Preliminary test results on composite leaf spring confirmed that long glass fibre reinforced PP leaf spring is able to carry three times the load for a design deflection than short glass fibre reinforced PP leaf spring. This improved spring rate behaviour results in significant improvement of the energy-absorbing capability. The influence of strain rate over the load deflection behaviour of long fibre reinforced leaf spring is found to be less than that of short fibre reinforced leaf spring. However, the damping behaviour of short glass fibre reinforced leaf spring is found to be superior to that of long glass fibre reinforced leaf springs.
Wave forces acting on a semi-submerged porous circular cylinder
Authors: Bao W , Kinoshita T , Zhao F
Published: June 2009

With potential applications in aquaculture as a sea cage or as floating breakwaters, a porous circular-cylinder semi-submerged in waves is investigated under the assumption of linear wave theory. To simplify the problem, the linear Darcy's law is applied to the porous boundary. The problem is solved by means of the eigenfunction expansion. The fluid domain is divided into two regions and different eigenfunctions are used. There are two horizontal porous plates in the inner region, i.e. the cover and bottom of the cylinder. This leads to a complicated ‘dispersion’ relation to determine the eigenvalues, the solutions of which are complex numbers. To solve the radiation problem, some particular solutions are sought to take account of the normal velocity of the body. The hydrodynamic forces are evaluated by integrating the pressure difference on the two sides of body surface. Computed examples are presented to observe the effects of porosity. The Haskind relations are examined for the porous body. It is found that the damping coefficient consists of two parts. In addition to the component of conventional wave-radiating damping, there exists a second component caused by the porous effects.
Non-linear wave-induced motions of cylindrical-shaped floaters of fish farms
Authors: Kristiansen D , Faltinsen O M
Published: June 2009

This paper addresses the two-dimensional hydrodynamical problem of a floating circular cylinder in waves by means of model tests and numerical simulations. The problem is relevant for floaters of fish farms. Dedicated model tests and computational fluid dynamics (CFD)-simulations, using a presently developed numerical wave tank are presented. Large amplitude sway motion of the cylinder at a wave frequency equal to half the natural sway frequency was observed, both experimentally and numerically. This is argued to be associated with non-linear hydrodynamic effects and instabilities. Further, linear potential flow theory is shown to overpredict the sway motion at resonance of about 500 per cent compared with experiments and simulations. This discrepancy is explained to be mainly attributable to viscous damping caused by flow separation. Higher-order harmonic components of the hydrodynamic forces are significant and should be considered in fatigue life analyses of fish farms.
Implicit expressions of static and incident wave pressures over the instantaneous wetted surface of ships
Authors: Du S X , Hudson D A , Price W G , Temarel P
Published: June 2009

To predict a ship's behaviour, adopting either a partial or comprehensive non-linear hydrodynamic method, requires accurate information of incident wave and static pressure on any location over the instantaneous wetted hull surface. In this study an implicit formula to evaluate the non-linear hydrostatic and incident wave dynamic pressures acting on a ship travelling in linear or second-order deep water incident waves is deduced based on a wave mapping method. The accuracy and efficiency of the numerical scheme of study employing this formula is verified and validated through comparisons with a simple extrapolation (or stretching) approach, Wheeler stretching methods, and with a fifth-order Stokes' wave theory, which is assumed to embody a more complete solution. More accurate predictions of the dynamic pressure are achieved from the proposed second-order wave mapping method. However, as a practical approach, the presented second-order wave Wheeler stretching method can be considered as a reasonable approximation to the proposed wave mapping method.
Synthesis of nanometre multi-layered ZrN/(Ti,Al)N coatings by ion-beam-assisted deposition
Authors: Cao M , Dong L , Liu G Q , Li D J
Published: June 2009

ZrN/(Ti, Al)N nanometre multi-layered coatings with different modulation ratios and ion beam fluxes have been synthesized by ion-beam-assisted deposition at room temperature. X-ray diffraction (XRD), a nano indenter, and a profiler were used to characterize the microstructure and mechanical properties of the coatings. The small-angle XRD pattern indicated a well-defined composition modulation and layer structure. The XRD pattern showed a significant mixture of strong ZrN(111) and (Ti,Al)N(111) textures. At an assisted beam flux of 5 mA and modulation ratio of 2:3, the ZrN/(Ti,Al)N multi-layer possessed the highest hardness (30.1GPa) and elastic modulus (361GPa). Its fracture resistance, and residual stress also showed the best results.
Limitations in the role of ulcer edge biopsy in establishing the aetiology of nontraumatic small bowel perforation
Authors: Sharma Sonal , Kotru Mrinalini , Batra Madhu , Gupta Archana , Rai Preeti , Sharma Rajeev
Published: June 2009

Spontaneous small intestinal perforations are common in India. Surgeons operating on patients with an obscure peritonitis should be aware of the diverse aetiologies of small intestinal perforations in order to be able to provide the appropriate management. We reviewed the pathology records of 165 patients operated on for nontraumatic perforations of the small intestines in our hospital between 2005 and 2007. Perforation edge biopsy was diagnostic in 53 cases, with typhoid being the most common aetiology, followed by TB. The majority of cases, however, revealed only a non-specific inflammatory granulation tissue. However, the sensitivity of biopsy diagnosis could be increased by taking additional biopsy material from the mesenteric lymph nodes, tubercles or omental nodules. We conclude that perforation edge biopsy is useful in a third of cases, but the diagnostic rate could be improved by taking additional biopsy material.
Amoebic liver abscesses complicated by inferior vena cava and right atrium thrombus
Authors: Khan Sadaf , Ameen Rauf Muhammad
Published: June 2009

Amoebiasis is a common protozoal infection that is endemic in South Asia. Hepatic involvement that manifests as abscess formation occurs in approximately 10% of all patients. Identified expeditiously, this can be treated with metronidazole. We present a case of multiple, large amoebic liver abscesses, that were complicated by thrombus formation in the inferior vena cava extending to the right atrium, requiring surgical removal.
Pulmonary nocardiosis presenting with cardiac tamponade and bilateral pleural effusion in a HIV patient
Authors: Chandrashekar U K , Acharya Vasudeva , Gnanadev N C , Varghese George K , Chawla Kiran
Published: June 2009

Nocardiosis induces a high mortality rate in those infected with HIV. It is now being increasingly described in patients with AIDS. Nocardia infection usually involves the lungs. In immunocompromised individuals it tends to disseminate. It mimics pulmonary TB both clinically and radiologically and many a time is wrongly treated with anti-tubercular drugs. Involvement of the pericardium is uncommon, having only been reported infrequently in the past. We describe a patient who presented with a cardiac tamponade and was confirmed as having pulmonary parenchymal and pleural disease.
Amputation surgery in children: an analysis of frequency and cause of early wound problems
Authors: Banza L N , Mkandawire N C , Harrison W J
Published: June 2009

Amputation surgery in children is a relatively uncommon procedure. The objective of our study was to determine the incidence of complications in this type of surgery as well as any related factors. The results of our retrospective study of children aged between one and 18 years, over a five-year period were collected and analysed. The most frequent indications for amputation were congenital limb deformities (60%). Trauma, tumours, infection and other rare conditions were less common.

Results also revealed that in our hospital the wound infection rate was 38 %, the wound breakdown rate was 11 % and the general wound sepsis rate was around 1%. More complications were observed following through-knee amputation. We had noticed fewer complications (25%) when the surgery was performed by a consultant than when it was performed by a junior trainee (66%).
The use of hospital medical records for child injury surveillance in northern Malawi
Authors: Yu Kwong Leung , Bong Chin Nam , Huang Meng Chuan , Chen Chih Cheng , Ko Ying Chin , Chang Po Ya , Chen Tai Heng , Chiang Hung Che
Published: June 2009

Our study evaluates the usefulness and the limitations of using the medical records of a central referral hospital to develop a child injury surveillance system in northern Malawi. The most prevalent types of injury were falls (29.6%), road traffic injuries (22.0%), burns (21.4%) and poisoning (15.1%). Older children (aged 5–14 years), in the cool-dry season (May to August) and the hot-dry season (September to October), were significant predictors for total injury admissions. Our study indicated that hospital medical records are a valuable component of a child injury surveillance system and can illustrate the trends and patterns of moderate to severe injuries as well as suggest potential prevention strategies for local settings. Combined with a specially designed trauma registry form, it is possible for developing countries at local level to combat the emerging public health issues.
The frequency of hepatitis D virus in patients with hepatitis B in Iran: an increasing rate?
Authors: Somi Mohammad H , Farhang Sara , Miri Seyyed Mohammad , Pouri Ali A , Mjidi Golnar , Alavian Seyyed Moayed
Published: June 2009

This study sought to determine the seroprevalence of the hepatitis D virus (HDV), the risk factors and its association with the severity of liver disease. Continuous patients at Tabriz and Tehran Hepatitis Clinics were enrolled during 2007–2008 in a cross-sectional study. Demographic data and possible risk factors for infection were recorded for all hepatitis B surface antigen positive patients. The blood samples of 847 patients infected with the hepatitis B virus were evaluated. The seroprevalence of HDV was 9.3%. This rate was significantly higher after reaching 40 years of age. The rate was 12.7% in patients with chronic hepatitis B and 4.7% in patients with in-active hepatitis B; the difference was statistically significant. A history of dental interventions and several trips abroad were good predictors of HDV infection in logistic regression. No significant difference in liver function tests was found. The seroprevalence of HDV was higher than in some other studies from Iran but a decrease was noted in younger age.
Variants of the Ffowcs Williams - Hawkings Equation and Their Coupling with Simulations of Hot Jets
Authors: Spalart Philippe R. , Shur Michael L.
Published: June 2009

The Ffowcs Williams - Hawkings (FWH) equation is often used in an inexact manner in numerical settings, because the amount of information available is limited. Generally the volume integral, or quadrupole term, is omitted even though the (permeable) FWH surface fails to enclose the turbulence region, which is unmanageably long for jet or bluff-body flows. This motivates a search for variants of the equation that are more forgiving of these practices, and thus more accurate at the same level of numerical effort. Two such variants are discussed, one proposed by Morfey in 1973 for other reasons, and the other used implicitly by Shur et al. since 2003. Both use functions of the pressure rather than the density in key terms, those which are retained in practice. The latter variant has similarities with proposals of Goldstein. They vastly reduce the need for cancellations between surface and volume terms, when entropy differences are present. There is no reason to use arbitrarily open surfaces. Sleeves can be made tight around the jet, without touching the vortical fluid, which is beneficial at high frequencies. There is little to choose between the two variants, as long as the quadrupoles are omitted. The benefits are illustrated in the case of a high-subsonic hot jet in co-flow, treated by Large-Eddy Simulation with extraction of the far-field sound by the classical FWH equation and by its variants, as well as with the Kirchhoff equation.
ANOPP Landing-Gear Noise Prediction with Comparison to Model-Scale Data
Authors: Burley Casey L. , Brooks Thomas F. , Humphreys William M. , Rawls John W.
Published: June 2009

The NASA Aircraft NOise Prediction Program (ANOPP) offers two empirically based methods to predict landing gear noise: the “Fink” method and the “Guo” method. The “Guo” method is the most recent and was developed almost exclusively using Boeing full-scale landing gear data. The “Fink” method was developed over 25 years ago, using both model and full-scale data. The details of the two methods are compared and contrasted. The Fink method is found to follow Strouhal scaling, and hence predictions are made with the scale model geometry as input. The Guo method was found not to scale for arbitrary sized landing gear and hence the method required full-scale geometry inputs and the resulting predictions required scaling in order to compare with the measured model results. Application of these methods to a model-scale landing gear is investigated by comparing predicted results from each method with measured acoustic data obtained for a high-fidelity, 6.3%-scale, Boeing 777 main landing gear. The measurements were obtained in the NASA Langley Quiet Flow Facility for a range of Mach numbers at a large number of observer angles. Noise spectra and contours as a function of polar and azimuthal angle characterize the directivity of landing gear noise. The measured spectra and contours are compared to predictions made using the Fink method and to scaled predictions from the Guo method. This is the first time an extensive set of landing gear noise directivity data are available to compare and assess predictive capabilities. Both methods predict comparable amplitudes and trends for the flyover locations, but deviate at sideline locations. Neither method fully captures the measured noise directivity.
Finding Your Way around Heritage Sites: The Delivery of Digital Information to Mobile Devices
Authors: Brown André , Knight Michael , Saeed Ghousia
Published: June 2009

An information enriched 3D digital city model connected wirelessly with the real-time user interaction has the potential to deliver an effective piece in the pervasive computing jigsaw. Real-time location awareness can contribute to the effective delivery of 3D digital city models and associated information to small mobile devices. Location awareness is also one of the vital elements of ubiquitous computing systems; together the mobile hardware and its interactive contents can be thought of as ‘everyware’ [1]. This paper describes the work -undertaken with different technological systems that have potential for pedestrian location sensing connecting the pedestrian user with real and virtual environments simultaneously. In particular we look at how users can be correctly located and efficiently informed about buildings and artefacts that are part of the spectrum of built forms that together are referred to as Architectural Heritage sites.
Modelling Behaviour of Configurable VR Applications
Authors: Walczak Krzysztof
Published: June 2009

Creation of complex behaviour-rich and meaningful content is one of the main difficulties that currently limit wide use of virtual reality technologies in everyday applications. To enable widespread use of VR applications new methods of content creation must be developed. In this paper, we propose a novel approach to designing behaviour-rich virtual reality applications, called Flex-VR. The approach enables building configurable VR applications, in which content can be easily created and modified by domain experts or even common users without knowledge about VR design and computer programming. The VR content is configured from reusable programmable content elements, called VR-Beans. Appearance and behaviour of the VR-Beans are controlled by scripts programmed in a novel high-level language, called VR-BML (Behaviour Modelling Language). The language enables specification of generic behaviours of objects that can be dynamically composed into virtual scenes. The paper introduces the Flex-VR component and content models, describes the VR-BML language and provides an example of a Flex-VR application in the cultural heritage domain.
An Intra-Individual Analysis of Players' Perceived Coaching Behaviours, Psychological Needs, and Achievement Goals
Authors: Wang C.K. John , Koh Koon Teck , Chatzisarantis Nikos
Published: June 2009

The purpose of this study was to examine the relations between perceptions of coaching behaviours, psychological needs, achievement goals and motivational indicators (enjoyment and effort) at an intra-individual level. A total of 264 high-school basketball players aged between 14 to 17 years old from 19 schools in Singapore took part in the study. The participants completed a battery of questionnaires measuring perceived coach's leadership style, achievement goals, behavioural regulations and competence, needs satisfaction, and enjoyment. Cluster analysis found 3 distinct groups differing in perceived coaching behaviours among the basketball players. The three clusters differed significantly on the indices of intrinsic motivation, perceived needs satisfaction, and achievement goals. This study shows that distinct groups of players could be identified in terms of perceived coaching behaviours and these perceptions may impact the amount of enjoyment and effort exerted during training and competition, perceived competence, achievement goals and autonomy.
Implications of Motor Unit Activity on Ballistic Movement
Authors: Wallace Brian , Janz Jonathon
Published: June 2009

In many competitive sports the ability to develop high amounts of force quickly is paramount to success. Ballistic methods of training have been employed by strength and sport coaches as a means of improving this performance characteristic. However, a thorough understanding of the body's responses to this type of training is necessary to adequately implement ballistic exercises into a physical training program. The scientific literature shows that the neuromuscular system behaves differently while performing ballistic movements than it does when performing movements requiring a lower velocity or rate of force development. This article aims to discuss nervous system muscle recruitment under progressive loading conditions, as well as high velocity and high rate of force development conditions acutely and chronically. It also provides programming suggestions regarding methods coaches could use to train athletes who participate in ballistic sports.
Examining the Ecological Validity of the Coaching Behavior Scale (Sports) for Basketball
Authors: Koh Koon Teck , Mallett Clifford , Wang C.K. John
Published: June 2009

This study examined the key tasks of high-performance basketball coaches in Singapore using the Coach Behavior Scale for Sports (CBS-S). Seventeen participants (national coaches, team managers, players and other experts) took part in the study in which quantitative (CBS-S) and qualitative (semi-structured interviews) data were collected. The quantitative data were analysed using SPSS (Version 15.0) and the qualitative data were content analysed by three experienced researchers in sport psychology and coaching. The dimensions and items from the CBS-S were considered mostly relevant in evaluating the work of Singapore high-performance basketball coaches. However, some modifications were made to the CBS-S to make it more specific to the basketball context in Singapore based on conceptual, theoretical and empirical considerations. The final version of the Singapore CBS-S (Basketball) has 9 dimensions with 96 items as opposed to the original CBS-S with 7 dimensions and 70 items. Overall, the findings from this study were consistent with the literature on coaches' work.
Perceptual Training Using Explicit and Implicit Instructional Techniques: Does it Benefit Skilled Performers?
Authors: Gorman Adam D. , Farrow Damian
Published: June 2009

This study investigated the efficacy of explicit and implicit perceptual training approaches designed to improve the pattern perception capabilities of skilled basketball players, relative to control and placebo groups. The explicit and implicit groups completed 4 weeks of training using temporally occluded video footage while the placebo group used general visual stimuli. Results from a video-based test showed no significant differences between the four groups after the training intervention, despite large absolute gains by the two experimental groups. After a 14-day retention interval, improvements by the control group suggested that test familiarity may have influenced the retention test results. The transfer data showed that the laboratory-based training failed to elicit a significant change in on-court performance. The results, while not statistically significant, highlight a number of key considerations when attempting to develop perceptual-cognitive abilities in experienced athletes and provide direction for researchers and practitioners when designing similar training approaches.
From the Editors…
Authors: Keller L. Robin , Kophazi Kelly M.
Published: June 2009

This issue's “From the Editors…” column is coauthored with Managing Editor Kelly Kophazi. In addition to introducing our articles, we report here on the past year from the perspective of the editorial office. The authors of the first three articles conducted laboratory experiments to examine decision behavior in financial investment decisions, bidding in auctions, and inventory ordering decisions. First, Dennis Vrecko, Alexander Klos, and Thomas Langer report on the “Impact of Presentation Format and Self-Reported Risk Aversion on Revealed Skewness Preferences.” Our second article is “A Direct Test of Risk Aversion and Regret in First Price Sealed-Bid Auctions,” by Richard Engelbrecht-Wiggans and Elena Katok. The third article, by Srinagesh Gavirneni and Yusen Xia, is on “Anchor Selection and Group Dynamics in Newsvendor Decisions—A Note.” Our final article, describing the application of decision analysis for an Italian waste processing decision, is “Resource-Limited Multiattribute Value Analysis of Alternatives for Immobilizing Radioactive Liquid Process Waste Stored in Saluggia, Italy,” by Alan J. Brothers, Shas V. Mattigod, Denis M. Strachan, Gordon H. Beeman, Paul K. Kearns, Angelo Papa, and Carlo Monti.
New Optimization Model and Algorithm for Sibling Reconstruction from Genetic Markers
Authors: Chaovalitwongse W. Art , Chou Chun-An , Berger-Wolf Tanya Y. , DasGupta Bhaskar , Sheikh Saad , Ashley Mary V. , Caballero Isabel C.
Published: June 2009

With improved tools for collecting genetic data from natural and experimental populations, new opportunities arise to study fundamental biological processes, including behavior, mating systems, adaptive trait evolution, and dispersal patterns. Full use of the newly available genetic data often depends upon reconstructing genealogical relationships of individual organisms, such as sibling reconstruction. This paper presents a new optimization framework for sibling reconstruction from single generation microsatellite genetic data. Our framework is based on assumptions of parsimony and combinatorial concepts of Mendel's inheritance rules. Here, we develop a novel optimization model for sibling reconstruction as a large-scale mixed-integer program (MIP), shown to be a generalization of the set covering problem. We propose a new heuristic approach to efficiently solve this large-scale optimization problem. We test our approach on real biological data as presented in other studies as well as simulated data, and compare our results with other state-of-the-art sibling reconstruction methods. The empirical results show that our approaches are very efficient and outperform other methods while providing the most accurate solutions for two benchmark data sets. The results suggest that our framework can be used as an analytical and computational tool for biologists to better study ecological and evolutionary processes involving knowledge of familial relationships in a wide variety of biological systems.
Parallel Stochastic Global Optimization Using Radial Basis Functions
Authors: Regis Rommel G. , Shoemaker Christine A.
Published: June 2009

We develop a parallel implementation of a stochastic radial basis function (RBF) algorithm for global optimization by Regis and Shoemaker [Regis, R. G., C. A. Shoemaker. 2007a. A stochastic radial basis function method for the global optimization of expensive functions. INFORMS J. Comput. 19(4) 497–509]. The proposed parallel algorithm is suitable for the global optimization of computationally expensive objective functions and does not require derivatives. Each iteration of the algorithm consists of building an RBF model to approximate the expensive function and using this model to select multiple points for simultaneous function evaluation on multiple processors. The function evaluation points are selected from a set of random candidate points according to two criteria: estimated function value based on the RBF model, and minimum distance from previously evaluated points and previously selected points within each iteration. We compare the performance of our parallel stochastic RBF algorithm against alternative parallel global optimization methods, including two multistart parallel finite-difference quasi-Newton methods, a multistart implementation of Asynchronous Parallel Pattern Search [Hough, P., T. G. Kolda, V. J. Torczon. 2001. Asynchronous parallel pattern search for nonlinear optimization. SIAM J. Sci. Comput. 23(1) 134–156], a parallel implementation of Probabilistic Global Search Lausanne [Raphael, B., I. F. C. Smith. 2003. A direct stochastic algorithm for global search. Appl. Math. Comput. 146 729–758], a parallel evolutionary algorithm, and a deterministic parallel RBF algorithm by Regis and Shoemaker [Regis, R. G., C. A. Shoemaker. 2007c. Parallel radial basis function methods for the global optimization of expensive functions. Eur. J. Oper. Res. 182(2) 514–535]. We report good results for our parallel stochastic RBF method when using one, four, or eight processors in comparison with the alternatives on 20 test problems and on 3 optimization problems involving groundwater bioremediation.
Simultaneous Batching and Scheduling Using Dynamic Decomposition on a Grid
Authors: Ferris Michael C. , Maravelias Christos T. , Sundaramoorthy Arul
Published: June 2009

Scheduling problems arise in many applications in process industries. However, despite various efforts to develop efficient scheduling methods, current approaches cannot be used to solve instances of industrial importance in reasonable time frames. The goal of this paper is the development of a dynamic decomposition framework that exploits the structure of the problem and is well suited for grid computing. The problem we study is the simultaneous batching and scheduling of multistage batch processes for which the binary decision variables are batch selection, batch-unit assignment, and batch sequencing on units. We present methods to decompose the original problem into a number of subproblems in a dynamic fashion. First, we discuss the generation of subproblems based on fixing the batch-selection variables. Second, we generate subproblems by fixing the batch-unit assignment variables in a bottlenecking stage. Third, we generate subproblems by fixing the last batch in the sequence on each unit of the bottlenecking stage. Furthermore, the second and third methods can be carried out in various combinations. Alternatively, a problem can be decomposed into a number of promising subproblems using an automatic strong branching scheme. Our results show that the proposed method can be used on a grid computer to solve large problems to optimality in a reasonable computational time.
An Empirical Analysis of Contract Structures in IT Outsourcing
Authors: Chen Yuanyuan , Bharadwaj Anandhi
Published: June 2009

Outsourcing of information technology (IT) services has received much attention in the information systems (IS) literature. However, considerably less attention has been paid to actual contract structures used in IT outsourcing (ITO). Examining contract structures yields important insights into how the contracting parties structure the governance provisions and the factors or transaction risks that influence them. Based on insights from prior literature, from practicing legal experts, and through in-depth content analysis of actual contracts, we develop a comprehensive coding scheme to capture contract provisions across four major dimensions: monitoring, dispute resolution, property rights protection, and contingency provisions. We then develop an empirical data set describing the contract structures across these distinct dimensions, using a sample of 112 ITO contracts from the Securities and Exchange Commission (SEC) database from 1993 to 2003.

Drawing on transaction cost, agency, and relational exchange theories, we hypothesize the effects of transaction and relational characteristics on the specific contractual provisions, as well as on overall contract extensiveness. Furthermore, we examine how these associations vary under conditions of fixed price and time and materials pricing structures. The results provide good support for the main hypotheses of the study and yield interesting insights about contractual governance of ITO arrangements.
Complementarities in the Diffusion of Personal Computers and the Internet: Implications for the Global Digital Divide
Authors: Dewan Sanjeev , Ganley Dale , Kraemer Kenneth L.
Published: June 2009

This paper studies the cross-country diffusion of personal computers (PCs) and the Internet, and examines how the diffusive interactions across these technologies affect the evolution of the global digital divide. We adopt a generalized diffusion model that incorporates the impact of one technology's installed base on the diffusion of the other technology. We estimate the model on data from 26 developing and developed countries between 1991 and 2005. We find that the codiffusion effects between PCs and the Internet are complementary in nature and the impact of PCs on Internet diffusion is substantially stronger in developing countries as compared to developed ones. Furthermore, our results suggest that these codiffusive effects are a significant driver of the narrowing of the digital divide. We also examine the policy implications of our results, especially with respect to how complementarities in the diffusion of PC and Internet technologies might be harnessed to further accelerate the narrowing of the global digital divide.
An Empirical Analysis of Software Vendors' Patch Release Behavior: Impact of Vulnerability Disclosure
Authors: Arora Ashish , Krishnan Ramayya , Telang Rahul , Yang Yubao
Published: June 2009

A key aspect of better and more secure software is timely patch release by software vendors for the vulnerabilities in their products. Software vulnerability disclosure, which refers to the publication of vulnerability information, has generated intense debate. An important consideration in this debate is the behavior of software vendors. How quickly do vendors patch vulnerabilities and how does disclosure affect patch release time? This paper compiles a unique data set from the Computer Emergency Response Team/Coordination Center (CERT) and SecurityFocus to answer this question. Our results suggest that disclosure accelerates patch release. The instantaneous probability of releasing the patch rises by nearly two and a half times because of disclosure. Open source vendors release patches more quickly than closed source vendors. Vendors are more responsive to more severe vulnerabilities. We also find that vendors respond more slowly to vulnerabilities not disclosed by CERT. We verify our results by using another publicly available data set and find that results are consistent. We also show how our estimates can aid policy makers in their decision making.
Research Note—Mapping the Field of Virtual Work: A Cocitation Analysis
Authors: Raghuram Sumita , Tuertscher Philipp , Garud Raghu
Published: June 2009

Interest in the area of virtual work continues to increase with articles being written from different disciplinary perspectives—e.g., information systems (IS), management, psychology, and transportation. In this paper, we map research on virtual work to (a) understand the intellectual base from which this field has emerged, (b) explore how this field has evolved over time, and (c) identify clusters of research themes that have emerged over time and the relationships between them. Specifically, we use cocitation analysis of research published in all social science disciplines to map the field at three points in time—1995, 2000, and 2006. Our results show that the field has grown from 9 research clusters in 1995 to 16 in 2006. A comparison across these maps suggests that research in the cluster of “virtual teams” has gained significance even as research in some earlier clusters such as “urban planning and transportation” has lost ground. Our longitudinal analysis identifies relevant concepts, theories, and methodologies that have emerged in the field of virtual work. This analysis can help interested researchers identify how they may want to contribute to the field of virtual work—by adding to popular clusters, by enriching emerging smaller clusters, or by acting as bridges across clusters.
Customer-Driven vs. Retailer-Driven Search: Channel Performance and Implications
Authors: Jiang Li , Anupindi Ravi
Published: June 2009

A common phenomenon that occurs in any decentralized multilocation system is stock imbalance, whereby some locations have unsatisfied demands while others are overstocked. The system can be rebalanced by using a search process that is driven by either the customers or the retailers. In a customer-driven search (CDS), the customer with unmet demand may search for the product at another location and, if it is available, complete the purchase. In a retailer-driven search (RDS), the retailer with unsatisfied demand searches for product and schedules transshipment to fulfill the unmet demand at his location. Of course, the revenues generated through search in RDS need to be shared between the parties according to a transfer pricing scheme. In a setting of one manufacturer and two retailers with price-dependent and random demand, we explore the impact of the search method and the transfer price scheme used on the preferences of the manufacturer, the retailers, and the customers. With endogenous retail prices, we find that both the manufacturer and the retailers prefer RDS over CDS when they can design the transfer pricing scheme in RDS. Interestingly, neither party prefers the fixed transfer pricing scheme commonly assumed in the literature. Instead, transfer price that is proportional to the price of the retailer with either excess stock or excess demand is preferred. However, although both parties favor an RDS system when they can design the transfer pricing scheme in RDS, they may prefer RDS or CDS when the other party designs the RDS. Thus, the interests of the manufacturer and the retailers are rarely aligned. Customers benefit from a lower price in an RDS but at the expense of lower availability (as measured by the level of safety stock).
Model‐based principal components of covariance matrices
Authors: Boik Robert J. , Panishkan Kamolchanok , Hyde Scott K.
Published: June 2009

A flexible class of models is proposed for principal component (PCs) of covariance matrices. The models allow constraints to be imposed on the eigenvalues and/or the eigenvectors and yield simplified PCs that retain their variance maximization and orthogonality properties. The models are fitted to sample covariance matrices by minimizing a discrepancy function. Asymptotic distributions of estimators are obtained under the assumption that fourth‐order moments of the parent distribution are finite. Hypothesis tests are obtained by comparing discrepancy functions that are minimized under different constraints. An Edgeworth expansion is used to obtain second‐order accurate confidence intervals for differentiable eigenfunctions. The techniques are illustrated on a real data set.
Book Review
Authors: von Koppenfels Martin
Published: June 2009

The Death of Sigmund Freud. The Legacy of His Last Days By Mark Edmundson London: Bloomsbury, 2007. Paperback £8.99. ISBN 978‐0‐74759‐2‐983
Book Review
Authors: Sarty Gordon
Published: June 2009

Introduction to structural equation modelling using SPSS and AMOS By Niels J. Blunch London: Sage Publications Ltd., 2008. Paperback £24.99. ISBN 978‐1‐41294‐557‐8
Book Review
Authors: Victor Janice M.
Published: June 2009

Working with ethnicity, race and culture in mental health: A handbook for practitioners By Hári Sewell Philadelphia, PA: Jessica Kingsley Publishers, 2009. Paperback £18.99. ISBN 978‐1‐84310‐621‐0
Contemporary utopian dreams: contemplating Staniewski's Golden Ass
Authors: Lease Bryce
Published: June 2009

This article contemplates Wodzimierz Staniewski's Metamorphoses as an adaptation of The Golden Ass of Apuleius. As Apuleius's text deals with a period of social and religious transition in the Roman Empire, Staniewski felt its themes were topical for modern-day Poland,
where people have suffered a tragic estrangement from the ground of their being. His primary aim is to utilize the figure of the goddess Isis as a mode of establishing a consistent identity for the subject vis--vis the collective unconscious in relation to the protagonist's double transformation:
humananimalhuman. My Lacanian analysis rejects this reading as an example of Jungian obscurantism that seeks to conceal the underlying utopian fantasy of unimpeded self-identity and social transparency; I argue that the unearthing of this fantasy in Staniewski's adaptation is the performance's
primary insight.
Queer beauty: illness, illegitimacy and visibility in Dickens's Bleak House and its 2005 BBC adaptation
Authors: Carroll Rachel
Published: June 2009

The visual plays a prominent role in the narrative of Charles Dickens's 1853 novel Bleak House; more specifically, a complex relationship between the visual and knowledge is integral to the identity intrigues at the core of Bleak House. This article will explore the relationship
between the visual economies (Robyn Wiegman) of Dickens's novel and its 2005 BBC adaptation. More specifically, it will focus on the relationship between illness, illegitimacy and the visible; it will suggest that the visible signs of Esther's illness, as inscribed on her face, can be read
as signifying an invisible condition: illegitimacy. This article will explore the ways in which this adaptation, as a neo-Victorian television drama, lends renewed visibility to issues of gender, power and legitimacy at work in Dickens's novel.