bluuebunny/crossref_metadata_2025_split huggingface dataset:
A discrete simulation model for assessing software project scheduling policies
Authors: Padberg Frank 
Published: December 2003

AbstractGood project scheduling is an essential, but extremely hard task in software management practice. In a software project, the time needed to complete some development activity is difficult to estimate. Often, the completion of activities is delayed due to unanticipated rework which is caused by feedback in the process.In this paper, we show how process simulation can be used to support managers in finding good schedules for their software projects. We present a novel, stochastic simulation model which is tailored to the special dynamics of software projects, and which explicitly takes a scheduling strategy as input. The model represents task assignments, staff skill levels, component coupling, and rework caused by design changes. The simulation model is implemented in theModLlanguage of the general‐purpose graphical simulation toolEXTEND.As an illustration of our simulation model, we study the performance of various list policies for a small sample project. The simulations quickly show the impact that the choice of the list policy will have on the progress and completion time of the sample project. To explain the performance difference between the list policies, we use the simulation traces to provide a detailed analysis of the task assignments which actually occur in the simulations. Copyright © 2003 John Wiley & Sons, Ltd.
A novel simulation model for the development process of open source software projects
Authors: Antoniades I. P. , Stamelos I. , Angelis L. , Bleris G. L. 
Published: December 2003

AbstractThe present paper presents a first attempt to produce a dynamical simulation model for the development process of open source software projects. First, a general framework for such models is introduced. Then, a specific simulation model is described and demonstrated. The model equations are based on available literature case studies whenever possible or reasonable assumptions when literature data are not adequate. The model is demonstrated against data obtained from a recent case study by A. Mockus, R. Fielding and J. Herbsleb (‘A case study of open source software development: the Apache server’) on the Apache www server software so as to reproduce quantitatively real results as closely as possible. Computer simulation results based on the calibrated model are thus presented and analysed. OSS dynamic simulation models could serve as generic predicting tools of key OSS project factors such as project failure/success as well as time dependent factors such as the evolution of source code, defect density, number of programmers and distribution of work effort to distinct project modules and tasks. Copyright © 2003 John Wiley & Sons, Ltd.
High‐level data races
Authors: Artho Cyrille , Havelund Klaus , Biere Armin 
Published: December 2003

AbstractData races are a common problem in concurrent and multi‐threaded programming. Experience shows that the classical notion of a data race is not powerful enough to capture certain types of inconsistencies occurring in practice. This paper investigates data races on a higher abstraction layer. This enables detection of inconsistent uses of shared variables, even if no classical race condition occurs. For example, a data structure representing a coordinate pair may have to be treated atomically. By lifting the meaning of a data race to a higher level, such problems can now be covered. The paper defines the concepts ‘view’ and ‘view consistency’ to give a notation for this novel kind of property. It describes what kinds of errors can be detected with this new definition, and where its limitations are. It also gives a formal guideline for using data structures in a multi‐threaded environment. © US Government copyright
Reformed undergraduate instruction and its subsequent impact on secondary school teaching practice and student achievement
Authors: Adamson Scott L. , Banks Debra , Burtch Mark , Cox Frank , Judson Eugene , Turley Jeffery B. , Benford Russell , Lawson Anton E. 
Published: December 2003

AbstractThe Arizona Collaborative for Excellence in the Preparation of Teachers (ACEPT) Program is one of several reform efforts supported by the National Science Foundation. The primary ACEPT reform mechanism has been month‐long summer workshops in which university and community college science and mathematics faculty learn about instructional reforms and then attempt to apply them in their courses. Previous ACEPT evaluation efforts suggest that, when implemented, the reforms boost undergraduate student achievement. The initial purpose of the present study was to discover whether enrollment of preservice teachers in one or more of these reformed undergraduate courses is linked to the way they teach after they graduate and become in‐service teachers. Assuming that a link is found, a second purpose was to discover whether the presumed positive effect is in turn linked to their students' achievement. In short, the answer appears to be yes, at least among the biology teachers and students surveyed. Compared with controls, the biology teachers who had enrolled in one or more ACEPT reformed course during their teacher preparation program demonstrated significantly higher scores on the measure of reformed instruction and their students demonstrated significantly higher achievement in terms of scientific reasoning, nature of science, and biology concepts. These results support the hypothesis that teachers teach as they have been taught. Furthermore, it appears that instructional reform in teacher preparation programs including both methods and major's courses can improve secondary school student achievement. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 939–957, 2003
Comparison of student performance using web and paper‐based homework in college‐level physics
Authors: Bonham Scott W. , Deardorff Duane L. , Beichner Robert J. 
Published: December 2003

AbstractHomework gives students an opportunity to practice important college‐level physics skills. A switch to Web‐based homework alters the nature of feedback received, potentially changing the pedagogical benefit. Calculus‐ and algebra‐based introductory physics students enrolled in large paired lecture sections at a public university completed homework of standard end‐of‐the‐chapter exercises using either the Web or paper. Comparison of their performances on regular exams, conceptual exams, quizzes, laboratory, and homework showed no significant differences between groups; other measures were found to be strong predictors of performance. This indicates that the change in medium itself has limited effect on student learning. Ways in which Web‐based homework could enable exercises with greater pedagogical value are discussed. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 1050–1071, 2003
Learning from inquiry‐based laboratories in nonmajor biology: An interpretive study of the relationships among inquiry experience, epistemologies, and conceptual growth
Authors: Wallace Carolyn S. , Tsoi Mai Yin , Calkin Jamie , Darley Marshall 
Published: December 2003

AbstractThe use of inquiry‐based laboratory in college science classes is on the rise. This study investigated how five nonmajor biology students learned from an inquiry‐based laboratory experience. Using interpretive data analysis, the five students' conceptual ecologies, learning beliefs, and science epistemologies were explored. Findings indicated that students with constructivist learning beliefs tended to add more meaningful conceptual understandings during inquiry labs than students with positivist learning beliefs. All students improved their understanding of experiment in biology. Implications for the teaching of biology labs are discussed. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 986–1024, 2003
The AS interactive project: single‐user and collaborative virtual environments for people with high‐functioning autistic spectrum disorders
Authors: Rutten Anja , Cobb Sue , Neale Helen , Kerr Steven , Leonard Anne , Parsons Sarah , Mitchell Peter 
Published: December 2003

AbstractThe AS Interactive Project aimed to assess the potential of single‐user and collaborative virtual environments to support learning and enhancing of social skills in people with autistic disorders on the high‐functioning end of the autistic spectrum. The project had two distinct phases of research: Phase I focused mainly on development and design using user‐centred principles. Phase II was concerned with implementation of design feedback, further improvements and evaluation studies of the virtual environments developed. This paper describes the research process, summarizes results of the project and briefly outlines plans for future research. Copyright © 2003 John Wiley & Sons, Ltd.
Development of a gait rehabilitation system using a locomotion interface
Authors: Yano Hiroaki , Kasai Kaori , Saitou Hideyuki , Iwata Hiroo 
Published: December 2003

AbstractA locomotion interface (LI) is a piece of equipment that can give a user the sense that he/she is walking while his/her actual position remains localized in the real world. We developed an LI system (GaitMaster2) that has two footpads, which can move to represent a virtual terrain for each user's foot. In this research, we applied our LI to gait rehabilitation. The footpads on our LI follow a pre‐recorded motion sequence to move the user's feet. We conducted evaluation tests with the assistance of hemiplegic patients. The effectiveness of our system was verified through EMG, video analysis and the measurement of physical values such as average velocity. Copyright © 2003 John Wiley & Sons, Ltd.
Energy efficient routing protocols for mobile ad hoc networks
Authors: Yu Chansu , Lee Ben , Yong Youn Hee 
Published: December 2003

AbstractAlthough establishing correct and efficient routes is an important design issue in mobile ad hoc networks (MANETs), a more challenging goal is to provide energy efficient routes because mobile nodes' operation time is the most critical limiting factor. This article surveys and classifies the energy‐aware routing protocols proposed for MANETs. They minimize either theactive communication energyrequired to transmit or receive packets or theinactive energyconsumed when a mobile node stays idle but listens to the wireless medium for any possible communication requests from other nodes.Transmission power control approachandload distribution approachbelong to the former category, andsleep/power‐down mode approachbelongs to the latter category. While it is not clear whether any particular algorithm or a class of algorithms is the best for all scenarios, each protocol has definite advantages/disadvantages and is well suited for certain situations. The purpose of this paper is to facilitate the research efforts in combining the existing solutions to offer a more energy efficient routing mechanism. Copyright © 2003 John Wiley & Sons, Ltd.
DSP implementation of successive interference cancellation (SIC) receiver for 3GPP WCDMA uplink transmission
Authors: Chang Yu‐jung , Lin Yu‐Nan , Lin David W. 
Published: December 2003

AbstractThe 3GPP WCDMA is a widely accepted third‐generation cellular system standard. By using nonorthogonal codes for different users, the multiple access interference (MAI) can be a limiting factor for system performance, as for other CDMA systems. Multiuser detection (MUD) is known to reduce MAI and improve CDMA system performance, but many such techniques have high complexity. Successive interference cancellation (SIC) is an effective MUD technique with relatively low complexity. We consider the software implementation of an SIC receiver for WCDMA uplink transmission on a commercially available general‐purpose multi digital signal processor (DSP) platform. This also goes in line with the recent interest in software‐defined radio. Issues addressed in this work include job partitioning and signal routing for multiprocessor implementation, design of SIC components (especially the channel estimator and the signal regenerator), determination of the precision of fixed‐point computations, consideration of the receiver's error performance and analysis of the implementation's complexity and efficiency. These issues are tightly coupled with the 3GPP WCDMA specifications. Because the employed platform only contains four DSPs, the implementation only considers up to three users. But this is sufficient for us to appreciate various DSP implementation issues of an SIC receiver. Moreover, by the nature of SIC, it is easy to extend the implementation to handle more users with an enlarged platform. Our present implementation achieves real‐time speed in the RAKE receiver part of the complete receiver. Due to the complexity in signal regeneration, the overall SIC receiver still falls short of the real‐time requirement when interference cancellation is activated. In fact, the platform employed presently cannot support real‐time processing when the number of multipaths is four or more, unless either the system architecture or the SIC algorithm is redesigned. Such and other ways of improvement are relegated to potential future work. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic resource allocation for CDMA‐TDD indoor wireless systems
Authors: Lee Chae Y. , Sung Ki Won 
Published: December 2003

AbstractFuture wireless communication systems are expected to provide a broad range of multimedia services that have a significant traffic asymmetry between uplink and downlink. The code division multiple access‐time division duplex (CDMA‐TDD) system is a promising solution to cope with the problem of traffic asymmetry. However, the TDD system is subject to inter‐cell interference compared to frequency division duplex (FDD) system. Since both uplink and downlink share the same frequency in TDD, uplink and downlink may interfere each other especially when neighboring cells require different rates of traffic load. Thus, the resource allocation among cells is an important issue in TDD. In this paper, the resource allocation in the CDMA‐TDD is formulated as a mixed integer programming (MIP) problem. A dynamic resource allocation algorithm (DRAA) is provided that effectively solves the traffic asymmetry problem. The MIP problem is also solved by a well‐known branch and bound procedure. Both the crossed slot and non‐crossed slot allocation are examined and compared to the DRAA. Computational result shows that proposed DRAA gives a good performance as the traffic asymmetry increases between the uplink and downlink. Copyright © 2003 John Wiley & Sons, Ltd.
Viscous and Aeroelastic Effects on Wind Turbine Blades. The VISCEL project. Part I: 3D Navier–Stokes Rotor simulations
Authors: Chaviaropoulos P. K. , Nikolaou I. G. , Aggelis K. A. , Soerensen N. N. , Johansen J. , Hansen M. O. L. , Gaunaa Mac , Hambraus T. , von Geyr Heiko Frhr. , Hirsch Ch. , Shun Kang , Voutsinas S. G. , Tzabiras G. , Perivolaris Y. , Dyrmose S. Z. 
Published: December 2003

AbstractAerodynamic modelling of HAWT rotors by means of “engineering methods” has reached a saddle point, where no further development can be expected without a breakthrough in understanding the physics of unsteady, rotating three‐dimensional flows. However, such a breakthrough becomes ever more necessary, as the size of the wind turbines increases. With the experimental work in that direction being mostly limited to observing the phenomena and interpreting the associated mechanisms, and its increased cost, alternatives are being sought. The use of CFD techniques and state‐of‐the‐art Navier–Stokes solvers is considered a very serious contender, a belief shared by the members of the present consortium, which has worked on the VISCEL JOR3‐CT98‐0208 Joule III project. This project's goal was to determine the aerodynamic characteristics as well as the aeroelastic behaviour of wind turbine blades across their broad range of operational conditions, from attached to highly separated flow regimes. The work programme included specific tasks for the validation and assessment of existing 3D solvers, for the parametric study of 3D flow around realistic blades and for the investigation of aeroelastic stability, at the blade section level. Copyright © 2003 John Wiley & Sons, Ltd.
The Use of a Code‐generating System for the Derivation of the Equations for Wind Turbine Dynamics
Authors: Ganander Hans 
Published: December 2003

AbstractFor many reasons the size of wind turbines on the rapidly growing wind energy market is increasing. Relations between aeroelastic properties of these new large turbines change. Modifications of turbine designs and control concepts are also influenced by growing size. All these trends require development of computer codes for design and certification. Moreover, there is a strong desire for design optimization procedures, which require fast codes. General codes, e.g. finite element codes, normally allow such modifications and improvements of existing wind turbine models. This is done relatively easy. However, the calculation times of such codes are unfavourably long, certainly for optimization use. The use of an automatic code generating system is an alternative for relevance of the two key issues, the code and the design optimization. This technique can be used for rapid generation of codes of particular wind turbine simulation models. These ideas have been followed in the development of new versions of the wind turbine simulation code VIDYN. The equations of the simulation model were derived according to the Lagrange equation and using Mathematica®, which was directed to output the results in Fortran code format. In this way the simulation code is automatically adapted to an actual turbine model, in terms of subroutines containing the equations of motion, definitions of parameters and degrees of freedom. Since the start in 1997, these methods, constituting a systematic way of working, have been used to develop specific efficient calculation codes. The experience with this technique has been very encouraging, inspiring the continued development of new versions of the simulation code as the need has arisen, and the interest for design optimization is growing. Copyright © 2003 John Wiley & Sons, Ltd.
Implications of the Regional Haze Rule on Renewable and Wind Energy Development on Native American Lands in the West
Authors: Acker Thomas L. , Auberle William M. , Duque Earl P. N. , Jeffery William D. , LaRoche David R. , Masayesva Virgil , Smith Dean H. 
Published: December 2003

AbstractA study conducted at Northern Arizona University investigated the barriers and opportunities facing Native American tribes in the West when considering development of their renewable energy resources in order to reduce regional haze. This article summarizes some of the findings of that work with special attention to wind energy. Background information is presented concerning the Regional Haze Rule and the Western Regional Air Partnership, and some of the circumstances surrounding development of tribal energy resources. An assessment of tribal energy issues revealed that many Native American tribes are interested in developing their renewable resources. However, this development should occur within the context of maintaining and strengthening their cultural, social, economic and political integrity. Furthermore, it is shown that Native American lands possess an abundant wind resource. A list of potential actions in which tribes may participate prior to or during development of their wind or renewable resources is provided. Copyright © 2003 John Wiley & Sons, Ltd.
Mercurous Azide, Hg2(N3)2
Authors: Nockemann Peter , Cremer Ulrich , Ruschewitz Uwe , Meyer Gerd 
Published: December 2003

AbstractWhite polycrystalline mercurous azide, Hg2(N3)2, is obtained by combining aqueous solutions of NaN3 and Hg2(NO3)2·2H2O (made viscuous by addition of tetramethoxysilane and heating at 65 °C). The crystal structure was solved and refined from X‐ray powder diffraction data (monoclinic, P21/n, a = 596.07(2) pm, b = 1259.07(4) pm, c = 357.95(1) pm, β = 103.253(2)°, Z = 2, RB = 0.0519). Solid Hg2(N3)2 contains, essentially, molecules of that composition with Hg‐Hg distances of 254.4(3) pm, Hg‐N distances of 218(2) pm and Hg‐Hg‐N angles of 178.7(6)°. Weak intermolecular interactions with Hg‐N distances starting at 280(3) pm lead to a three‐dimensional structure.
Synthesis and Crystal Structures of Palladium(II) Complexes of Macrobicyclic Azathiaether Ligands
Authors: Siedle Gabriel , Kersting Berthold 
Published: December 2003

AbstractThe macrobicyclic azathioether ligands L1 and L2 were investigated regarding their capability to form complexes with divalent palladium. L1 represents a cyclophane‐like ligand system comprising two 4‐tert‐butyl‐2, 6‐bis(aminomethyl)thiophenolate units, which are linked by an ethylene and two 3‐aza‐1, 5‐pentylene units to give two seventeen‐membered dithia‐triaza crowns fused at the common ArSCH2CH2SAr fragment. L2 is the hexa‐N‐methylated derivative of L1. Treatment of L1 and L2 with two equivalents of [PdCl2(CH3CN)2] gave the new complexes [(L1)Pd2Cl]+ (1) and [(L2)Pd2Cl2]2+ (2), respectively, which were isolated as perchlorate salts and characterized by elemental analysis, IR and NMR spectroscopy and by X‐ray crystallography. In 1, L1 acts as a septadentate ligand to give two distorted square‐planar PdN3S and PdN3Cl units, respectively. The structure of 2 shows L2 to be hexacoordinate, yielding two distorted square‐planar PdN2SCl units leaving two NMe groups dangling. NMR spectroscopic studies reveal that both complexes retain their solid‐state structures in solution. The reaction of L2 with one equivalent of [PdCl2(CH3CN)2] is accompanied by a bond cleavage reaction of one of the two aliphatic thioether bonds to afford the dinuclear complex [(L3)Pd2Cl2]Cl (3·Cl) of the ring‐opened 24‐membered hexaaza‐vinylthioether/thiophenolate derivative (L3)‐. The crystal structure determination of 3·Cl reveals two distorted‐square planar PdN2ClS units which are bridged by the thiophenolate sulfur atom of (L3)‐. The vinyl‐thioether moiety and the two remaining amine donors of (L3)‐ do not interact with the two palladium ions. The X‐ray structure analysis of the free macrocycle L2 demonstrates that the C‐S bond lengths become elongated upon coordination to the palladium(II) ions.
Diaza Crown Ethers and Cryptants as Bridging Ligands in Lamellar Copper(I) Coordination Polymers
Authors: Mühle Jörg , Sheldrick William S. 
Published: December 2003

AbstractCuX‐based coordination polymers (X = I, CN, SCN) with diazacrown ethers or cryptands as bridging ligands have been prepared by reaction of CuX with appropriate macrocycle in acetonnitrile/hexane solution at 100 °C. Whereas [CuI (1, 7‐DA12C4)] (1) and [CuI(1, 10‐DA18C6)] (2) (1, 7‐DA12C4 = 1, 7‐diaza‐12‐crown‐4, 1, 10‐DA18C6 = 1, 10‐diaza‐18‐crown‐6) are both monomeric, [(CuI)2(1, 10‐DA18C6)] (3) contains infinite chains in which (CuI)2 rings are linked in a μ‐N1, N10 manner by thiacrown ether moieties. The distorted tetrahedral coordination of the CuI atoms in 3 is completed by a weak Cu…O interaction (2.393(7)Å) to a 1, 10‐DA18C6 oxygen atom. [(Cu4I4)(1, 10‐DAcrypt)2] (4), (1, 10DAcrypt = 1, 10‐diaza‐cryptand [2.2.2]), [{(CuCN)6(1, 7‐DA12C4)4]·2CH3CN (5) and [(CuSCN)2 (1, 10‐DA18C6] (6) all exhibit lamellar networks with respectively Cu4I4 cubes, (CuCN)6 hexagons and [(CuSCN)2] double chains as their CuX substructures. 4 can imbibe up to 0.64 mol KNO3/mol cryptand and 6 up to 0.35 mol KNO3/mol 1, 10‐DA18C6 as a guest lattice. Crystal structures are reported for 1‐6, thermal analysis data (TG/DTA) for complexes 2, 3 and 5.