bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental assessment of differences between related protein crystal structures
Authors: Kleywegt Gerard J.
Published: July 2002

Prior to attaching any biological significance to differences between two related protein crystal structures, it must be established that such differences are genuine, rather than artefacts of the structure-determination protocol. This will be all the more important as more and more related protein structures are solved and comparative structural biology attempts to correlate structural differences with variations in biological function, activity or affinity. A method has been developed which enables unbiased assessment of differences between the structures of related biomacromolecules using experimental crystallographic information alone. It is based on the use of local density-correlation maps, which contain information regarding the similarity of the experimental electron density for corresponding parts of different copies of a molecule. The method can be used to assess a priori which parts of two or more molecules are likely to be structurally similar; this information can then be employed during structure refinement. Alternatively, the method can be used a posteriori to verify that differences observed in two or more models are supported by the experimental information. Several examples are discussed which validate the notion that local conformational variability is highly correlated to differences in the local experimental electron density.
Optimization of the critical nuclear size for protein crystallization: a note
Authors: Saridakis Emmanuel
Published: July 2002

It was observed that for some proteins the best crystals for X-ray diffraction have been obtained at supersaturation ratios of ca 2.5–3 (in experiments without seeding). It was then noticed that under certain conditions specific to the protein such values are close to a local minimum of the critical radius for nucleation. A relation between the two observations is proposed.
Local structure of guest molecules in gas hydrates – a model study of Kr and Xe clathrates
Authors: Montano P. A. , Linton J. , Thieu V. , Halpern Y.
Published: July 2002

Gas hydrates constitute a class of solids in which small molecules occupy cavities inside an ice-like structure. There is enormous scientific and technological interest in understanding the structure, stability and formation mechanism of clathrates. A variable-temperature high-pressure cell for X-rays measurements has been developed and constructed, which allows in situ studies of clathrate formation or decomposition. XAFS and diffraction techniques have been used to study the evolution of the structure during formation and decomposition. Two clathrates structures were studied, structure I (Xe) and structure II (Kr), and the local structure around the guest atom was identified. The rare gas-water complexes that act as precursor to the formation of the crystalline phases were identified. The transformation of the clathrate from structure II to structure I when Xe is added to Kr clathrates was observed.
Site-selective XAFS spectroscopy tuned to surface active sites of Cu/ZnO and Cr/SiO2 catalysts
Authors: Izumi Yasuo , Nagamori Hiroyasu , Kiyotaki Fumitaka , Minato Taketoshi
Published: July 2002

XAFS (X-ray absorption fine structure) spectra were measured by using the fluorescence spectrometer for the emitted X-ray from sample. The chemical shifts between Cu0 and CuI and between CrIII and CrVI were evaluated. Tuning the fluorescence spectrometer to each energy, the Cu0 and CuI site-selective XANES for Cu/ZnO catalyst were measured. The first one was similar to the XANES of Cu metal and the second one was the 5 : 5 average of XANES for CuI sites + Cu metal. The population ratio of copper site of the Cu/ZnO catalyst was found to be Cu metal : Cu2O : CuI atomically dispersed on surface = 70(±23) : 22(±14) : 8(±5). Site-selective XANES for CrIII site of Cr/SiO2 catalyst was also studied.
Theoretical studies of core excitation and ionization in molecular systems
Authors: Lin Ping , Lucchese Robert R.
Published: July 2002

Photoionization cross sections have been computed using correlated initial and final target states obtained with standard ab initio techniques and using a numerical representation of the continuum scattering orbitals. Here, core ionization of small molecular systems will be focused on. A brief review of previous results obtained using these methods is given. New results are then given for the N 1s ionization of NO and the N 1s ionization of N2. In the study of NO, the spin-coupling scheme which best describes the shape-resonant state and the energy dependence of the branching ratios for the singlet and triplet final ion states will be considered. In the study of N2 core ionization, the effects of the coupling of nearly degenerate core levels and the effects of correlation on the importance of interchannel coupling will be considered.
Magnetic-field modulation experiments on colossal magnetoresistance samples: first results
Authors: Bridges Frank , Brown Graham , Cao Daliang , Anderson Mark
Published: July 2002

Recently we have observed a small change in the width, σ, of the Mn-O pair distribution function when a 1T magnetic field is applied. To improve our sensitivity to magnetic-field-induced changes, we have developed a magnetic field modulation technique. At each X-ray energy we collect two data points, one with field on and the other with field off; as a result we collect two scans simultaneously. The difference in these two traces provides a measure of the magnetic-field-induced change. The results for the modulation measurements will be compared to the earlier work using static magnetic fields.
Atomic background and EXAFS of gaseous hydrides of Ge, As, Se and Br
Authors: Prešeren Rok , Kodre Alojz , Arčon Iztok , Borowski Michael
Published: July 2002

K edge absorption spectra of elements from Ge to Br in gaseous hydrides were measured at the BM 29 station of ESRF with noise level as low as 2 × 10−5, so far achievable only on noble gases. The dominant feature of the spectra is the atomic background similar to that of Kr and comparable to it in the quality of detail. Onto the background, a smooth weak EXAFS signal due to the hydrogen neighbors is superposed. For the very simple molecules such as these, its contribution can be calculated ab initio, with exact treatment of the effect of molecular vibrations, so that no best-fit adjustment to the experimental data is necessary. In comparison to the main constituent of the atomic background, i.e. the shake-up absorption edges, the EXAFS signal is of minor importance in HBr with a single H neighbor, but of the same order of magnitude in GeH4.
Hole counts from X-ray absorption spectra
Authors: Ankudinov A. L. , Nesvizhskii A. I. , Rehr J. J.
Published: July 2002

The interpretation of X-ray absorption spectra in terms of electronic structure has long been of interest. Hole counts derived from such spectra are often interpreted in terms of free-atom occupation numbers or Mülliken counts. It is shown here, however, that renormalized-atom (RA) and cellular counts are better choices to characterize the configuration of occupied electron states in molecules and condensed matter. A projection-operator approach is introduced to subtract delocalized states and to determine quantitatively such hole counts from X-ray absorption spectra. The described approach is based on multiple-scattering theory (MST) and on atomic calculations of a smooth transformation relating the X-ray absorption spectra to local projected densities of states (LDOS). Theoretical tests for the s and d electrons in transition metals show that the approach works well.
Mn K-edge XMCD in Mn3
MC (M = Zn and Ga) perovskite
Authors: Uemoto Shinji , Maruyama Hiroshi , Kawamura Naomi , Uemura Shigeaki , Kitamoto Naoya , Nakao Hideki , Hara Shoji , Suzuki Motohiro , Fruchart Daniel , Yamazaki Hitoshi
Published: July 2002

Mn3
MC (M = Zn and Ga) perovskite has attracted interest because of a variety of magnetic phase transitions. In this work, we measure temperature and magnetic field dependence of X-ray magnetic circular dichroism (XMCD) at Mn K-edge and discuss effect of second constituent metal on the magnetic states of Mn atoms. The spectrum in Mn3ZnC is characterized by a dispersion-type profile. In Mn3GaC, intensity of the positive peak at the edge is drastically reduced. The difference originates in charge transfer from Zn or Ga to Mn atoms. Temperature and magnetic field variations of the Mn K-edge XMCD spectrum suggest that orbital magnetic moments are closely related to the magnetic phase transition.
Local structure analyses of Ce0.5Zr0.5O2 mixed oxides by XAFS
Authors: Nagai Yasutaka , Yamamoto Takashi , Tanaka Tsunehiro , Yoshida Satohiro , Nonaka Takamasa , Okamoto Tokuhiko , Suda Akihiko , Sugiura Masahiro
Published: July 2002

Three types of CeO2-ZrO2 with the same composition (Ce/Zr = 1) were prepared by different methods, exhibited the different oxygen storage/release capacity (OSC). To investigate the relationship between the OSC and the local structure, the Ce and Zr K-edges XAFS spectra for these samples were measured. The features of Fourier transforms of these samples were different from each other. This suggested that the OSC was remarkably exerted by the local structure around Ce and Zr. The quantitative curve-fitting analysis of EXAFS was applied, and it was concluded that homogeneous Ce0.5Zr0.5O2 solid solution at atomic level exhibited the highest OSC among these CeO2-ZrO2 with the same composition (Ce/Zr = 1).
Prospects for X-ray absorption with the super-bright light sources of the future
Authors: Norman David
Published: July 2002

The immense growth in applications of X-ray absorption spectroscopy (XAS) has been enabled by the widespread availability of intense tunable X-rays from synchrotron radiation sources. Recently, new concepts have been proposed for fourth-generation light sources, such as the SASE (self-amplified stimulated emission) X-ray free-electron lasers (XFELs) being pursued at Hamburg (TESLA) and Stanford (LCLS), and the recirculator ring (MARS) at Novosibirsk. These sources offer expected gains of many orders of magnitude in instantaneous brilliance, which will unlock opportunities for qualitatively different science. Examples of new or greatly expanded techniques in XAS could include Raman X-ray absorption fine structure (XAFS), pump-probe experiments, time-resolved XAFS and small-spot X-ray spectromicroscopy, although the limited tunability of the sources might not allow conventional XAFS measurements. Multi-photon X-ray absorption could become a new field of study. There should not be a collective stampede to these new sources, however, and it is likely that storage rings will continue to be necessary for most XAFS applications. The extreme brightness of these future light sources will present difficult challenges in instrumentation, especially detectors and sample containment. Practitioners will also have to exercise caution, because the intensity of the beam will surely destroy many samples and in some cases there will be so many photons absorbed per atom that XAFS will be impossible.
Crystallization process of transparent conductive oxides ZnkIn2Ok+3
Authors: Moriga Toshihiro , Fukushima Akihiko , Tomonari Yozo , Hosokawa Shoji , Nakabayashi Ichiro , Tominaga Kikuo
Published: July 2002

Crystallization process of the homologous compounds ZnkIn2Ok+3 from the coprecipitants was examined by XAFS spectroscopy and X-ray diffractometry. Interesting crystallization behavior could be observed. Though zinc oxide already crystallized as the wurtzite-type ZnO at 573K, indium oxide remained amorphous. Subsequently bixbyite-type In2O3 appeared at 873K for k=5 and 7 and at below 773K for the other k-members, respectively. The In-O distance in the amorphous In2O3 was a little shorted than that in the bixbyite-type In2O3 by 0.06-7Å. The distance remained constant but abruptly increased to that observed in the bixbyite-type In2O3 in accordance with the progress of crystallization. Then the distance gradually decreased and converged to ca. 2.12Å at the temperature range of 1173-1373K, due to the reaction between In2O3 and ZnO to form the homologous compound.
EXAFS study of phase transitions in KIO3
Authors: Yagi Kenichiro , Umezawa Shunsuke , Terauchi Hikaru , Kasatani Hirofumi
Published: July 2002

The iodine K-edge EXAFS study of KIO3$ was performed to clarify local structural changes on the successive phase transitions. The pair-distribution function of three oxygen atoms in an oxygen octahedron is almost independent on temperature like a covalent bond, whereas that of the other three is gradually reduced with increasing temperature like an ionic bond. The result indicates that iodine and oxygen atoms exist as an IO3
− molecule in a pseudo-perovskite-type structure. The anomalous behavior in the Debye-Waller factor for the latter pair-distribution function appears around 50 K, which is associated with the orientational glass transition.
XAS and MCD studies in Eu0.6Sr0.4MnO3
Authors: Mizumaki Masaichiro , Saitoh Yuji , Agui Akane , Yoshii Kenji , Fujimori Atsushi , Nakamura Shin
Published: July 2002

Eu1-xSrxMnO3 system is one of the perovskite manganites that exhibit the giant magneto resistance effect and the transition from the insulator phase to the metal. Eu0.6Sr0.4MnO3 behaves as a ferromagnetic semiconductor and has an Insulator-Metal (IM) transition induced by external magnetic field, which could be found only in this system among the perovskite manganites group. The mechanism of the transition was investigated by X-ray Magnetic Circular Dichroism (XMCD) at the Mn L
2,3-edges of and the Eu M
4,5 -edges in Eu0.6Sr0.4MnO3.
Applications of combined EXAFS and powder diffraction analysis in solid state chemistry
Authors: Binsted Norman , Stange Marit , Owens Craig , Fjellvåg Helmer , Weller Mark T.
Published: July 2002

Recent applications of combined EXAFS/powder neutron and X-diffraction analysis are reviewed and provisional results for three additional compounds are presented. Criteria for successful refinements are suggested. The new results relate to the materials: CoAl2O4, La6.4Ca1.6Cu6Ni2O20 and Pr0.5Sr0.5FeO2.75.
Chromium speciation in residues after sequential extraction of a thermally treated sludge analog
Authors: Wei Yu-Ling , Yang Yaw-Wen , Lee Jyu-Fu , Huang Mu-Yu , Hsu Lee-How
Published: July 2002

XANES fitting indicates that non-Cr2O3 form of Cr(III), transformed from CrO3 by four-hour heat application at 1100°C, is the key species sorbed onto or lattice-diffused into kaolin matrices that exhibits strong leaching resistance to sequential extraction using various combined solutions including HNO3, H2O2, and HF. The EXAFS spectra are all in agreement with the XANES results. It is suggested that some Cr2O3 might have reacted with kaolin to form new compounds such as Cr2O3 ˙Al2O3 ˙2SiO2 to account for the slight dissimilarity between the EXAFS spectra of samples and that of Cr2O3.
Multiple scattering approach to K-edge XANES of Sb–Te systems
Authors: Hayakawa Kuniko , Fujikawa Takashi , Iwata Noriyuki , Tani Katsuhiko
Published: July 2002

The Sb-Te systems are important for optical memories. The local structures of these Sb-Te systems are crucial to understand the properties. Here we study three different Sb-Te systems, Sb2Te3, c- and a-SbTe (c; crystalline, a; amorphous) by use of XANES analyses. The present calculations for Sb2Te3 system show quite good agreement with the observed spectra. In contrast to Sb2Te3 system, both c- and a-SbTe systems, in which a ratio of Sb to Te is 3, are metastable; both of the structures have not been known yet. We thus investigate these local structures by use of the multiple scattering approach, and propose a possible model for each of c- and a-SbTe.
High-resolution hard X-ray phase-contrast microscopy with a large-diameter and high-numerical-aperture zone plate
Authors: Kagoshima Yasushi , Yokoyama Yoshiyuki , Ibuki Takashi , Niimi Toshihiro , Tsusaka Yoshiyuki , Takai Kengo , Matsui Junji
Published: July 2002

An imaging transmission hard X-ray microscope has been constructed at beamline BL24XU of SPring-8. It makes use of a phase zone plate made of tantalum with a diameter of 1 mm and an outer-most zone width of 50 nm, aiming at a wide field of view and a high spatial resolution. The performance test was carried out at a photon energy of 10 keV. A field of view as wide as ∼200 µm in diameter was achieved. The spatial resolution was measured to be 220 nm by analyzing a knife-edge image. Further, a line-and-space pattern as fine as 100 nm could be imaged. By placing a phase plate made of gold in the back focal plane of the zone plate, phase-contrast microscopy using Zernike's method was also carried out. The feasibility of phase-contrast microscopy for observing transparent samples was successfully demonstrated by imaging small polystyrene particles.
DAFS Experiments with Non-Centrosymmetric Single Crystals
Authors: Meyer Dirk C. , Richter Kurt , Seidel Andreas , Weigelt Jörg , Frahm Ronald , Paufler Peter
Published: July 2002

Diffraction anomalous fine structure (DAFS) experiments were applied to an epitaxially grown (Ga,In)P layer on a [001] GaAs substrate as a single-crystalline model substance. The requirements for the reliable measurement of reflection intensities as a function of photon energy, as well as the quantitative DAFS analysis resulting in the complex-valued fine-structure function of the scattering factor, are described. In the case of single crystals, effort had to be put into performing the DAFS measurements in order to hold the position of the Bragg reflection exactly during the energy scan. Using the zinc-blende-type structure as an example, it is shown for the first time that, similar to single-crystal structure analysis, the lack of inversion symmetry has a significant impact on the DAFS signal, so that DAFS may contribute to structure analysis as well.
Learning alliances: a customer‐supplier focus for continuous improvement in manufacturing
Authors: Love Peter E.D. , Gunasekaran A.
Published: July 2002

The manufacturing industry is becoming increasingly competitive. In order to remain competitive there is a need for improved inter‐organizational relations between organizations so as to improve the performance. In an attempt to improve cost effectiveness and improve quality, as well as create a long‐term competitive advantage, manufacturing organizations are beginning to initiate strategic alliances with their customers and suppliers as part of their supply chain management. This paper suggests that the key to gaining a competitive advantage and improving customer satisfaction lie with the ability of manufacturing organizations to form learning alliances. Essentially, learning alliances are strategic partnerships that are based on creating an environment that encourages mutual and reflective learning between supply chain partners. It is suggested that an alliance based on cooperation can encourage higher levels of trust and commitment. This paper presents a learning framework founded on total quality management for the formation of cooperative alliances between manufacturing organizations in a supply chain. The implications of forming a learning alliance in manufacturing are discussed.
The personnel function in the universities of northern England
Authors: Mackay Lesley
Published: July 2002

Only recently has a professional personnel function become
established within UK universities. Based on interviews with heads of
the personnel function in both “old” and “new”
universities in northern England, discusses the approach being taken to
personnel management in higher education. Presents evidence of changes
in style and direction of the personnel function and considers the
possibility of convergence between the two types of university.
Downsizing, delayering ‐ but where’s the commitment?
Authors: Thornhill Adrian , Saunders Mark N.K. , Stead Jo
Published: July 2002

Considers the pursuit of high quality, flexibility and employee commitment alongside significant downsizing and delayering initiatives. Examines the impact on surviving employees in downsized and delayered organizations. Proposes that organizations need to be more mindful than they have been in the past of survivor responses and issues. Contends that the espoused aim of many organizations to achieve employee commitment may be dependent largely on the degree of success with which organizations overcome survivor responses which are negatively oriented towards them. Explores the scope for organizational action to address issues which the workforce believes are important, suggesting that this should help organizations to engender positive survivor responses and organizational commitment. Reports how findings from qualitative research have been used to develop a diagnostic tool to help organizations assess their own ability to manage these factors and to influence survivor commitment. Discusses the use and validity of this tool. Concludes by emphasizing the need for organizations to be aware of and to respond to these issues and their effects. Highlights the importance of developing the strategy to rebuild survivors’ commitment over a longer term.
Employee selection: a question of structure
Authors: Barclay Jean M.
Published: July 2002

The first part of a larger study into organisations’ use of structured interviewing techniques. Discusses reasons for continued popularity of interviewing in selection, despite its shortcomings. Considers the use of two structured interviewing techniques to improve selection: behavioural and situational questioning. Presents the findings of a large scale survey of UK organisations’ use of these techniques. The use of structured interviewing is rapidly increasing and is used by all sizes of organisation. Behavioural interviewing is being used more than situational interviewing, and many respondents use both techniques. Structured techniques are most commonly used for management posts. Discusses links with competency based HRM and roles of line managers and HR specialists in selection. Areas for further research are outlined.
The reality of equal opportunities
Authors: Skinner Denise
Published: July 2002

Part‐time work has been the major area of employment growth during the last decade and now forms almost one‐quarter of total employment in the UK. Within the literature it is argued that a key aspect of the growth of part‐time work is its role in enabling an organisation to meet the diverse needs of its workforce. But to what extent does the reality match the aspirations? Using questionnaires and in‐depth interviews, the expectations and experiences of part‐time staff in a large public sector organisation and their managers are explored. The findings reveal practical difficulties inherent in meeting the diverse needs of the workforce including hidden costs, conflict between the needs of full‐time and part‐time staff and inequality caused by the “level playing field” approach. The research also identified the importance of non‐standard hours to these employees, which may reduce pressure on employers to find solutions to the problems.
“Soft” grasping using a dextrous hand
Authors: Caldwell D.G. , Tsagarakis N.
Published: July 2002

Manipulators in one form or another have been in existence for many hundreds of years with the design usually motivated by the task to be undertaken. Most often in robots this has led to a simple two fingered claw mechanism which has been adequate for many tasks but when the problem domain includes a varied range of delicate or easily damaged objects, one approach is to emulate those attributes of the human hand which make it such a versatile end‐effector. This paper will study two aspects of manipulator design: the construction of a dextrous hand with multi degree of control prehension, and the actuation systems to drive this hand that will make use of complaint drives to produce a “soft” but highly flexible mechanism to handle delicate products and materials.
Manipulator visual servoing and tracking of fish using a genetic algorithm
Authors: Minami Mamoru , Agbanhan Julien , Asakura Toshiyuki
Published: July 2002

This paper presents the real‐time visual servoing of a manipulator and its tracking strategy of a fish, by employing a genetic algorithm (GA) and the unprocessed gray‐scale image termed here as “raw‐image”. The raw‐image is employed to shorten the control period, since it has more tolerance of contrast variations occurring within an object, and between one input image and the next one. GA is employed in a method called 1‐step‐GA evolution. In this way, for every generational step of the GA process, the found results, which express the deviation of the target in the camera frame, are output for control purposes. These results are then used to determine the control inputs of the PD‐type controller. Our proposed GA‐based visual servoing has been implemented in a real system, and the results have shown its effectiveness by successfully tracking a moving target fish.
Colour statistics of natural and man‐made surfaces
Authors: Westland Stephen , Shaw Julian , Owens Huw
Published: July 2002

The reflectance spectra of natural and man‐made surfaces are highly constrained. Statistical analyses have been conducted that confirm that the surface reflectance spectra form a set of band‐limited functions with a frequency limit of approximately 0.02 cycles/nm. The reflectance spectra can be represented by a linear‐model framework and are adequately described by 6‐12 basis functions. However, the spectral properties of surfaces are not so constrained as to allow the human visual system to recover the surface properties from cone excitations. Furthermore, trichromatic colour devices such as scanners and cameras can only capture illumination‐specific colour information.
Numerical modelling of mass transfer in slits with semi‐permeable membrane walls
Authors: Geraldes Vítor , Semião Viriato , Norberta Pinho Maria
Published: July 2002

A mathematical model to predict the concentration polarisation in nanofiltration/reverse osmosis is described. It incorporates physical modelling for mass transfer, laminar hydrodynamics and the membrane rejection coefficient. The SIMPLE algorithm solves the discretised equations derived from the governing differential equations. The convection and diffusive terms of those equations are discretised by the upwind, the hybrid and the exponential schemes for comparison purposes. The hybrid scheme appears as the most suitable one for the type of flows studied herein. The model is first applied to predict the concentration polarisation in a slit, for which mathematical solutions for velocities and concentrations exist. Different grids are used within the hybrid scheme to evaluate the model sensitivity to the grid refinement. The 55×25 grid results agree excellently for engineering purposes with the known solutions. The model, incorporating a variation law for the membrane intrinsic rejection coefficient, was also applied to the predictions of a laboratory slit where experiments are performed and reported, yielding excellent results when compared with the experiments.
Implementing finite element methods on supercomputers, workstations and PCs: a bibliography (1985‐1995)
Authors: Mackerle Jaroslav
Published: July 2002

Presents a review on implementing finite element methods on supercomputers, workstations and PCs and gives main trends in hardware and software developments. An appendix included at the end of the paper presents a bibliography on the subjects retrospectively to 1985 and approximately 1,100 references are listed.
An overview of microvia technology
Authors: Lau John H. , Chang Chris
Published: July 2002

There are many advantages of microvia: it requires a much smaller pad, which saves the board size and weight; with microvia, more chips can be placed in less space or a smaller PCB, which results in a low cost; and with microvia, electrical performance improves due to a shorter pathway. Basically, there are five major processes for microvia formation: NC drilling; laser via fabrication including CO2laser, YAG laser, and excimer; photo‐defined vias, wet or dry; etch via fabrications including chemical (wet) etching and plasma (dry) etching; and conductive ink formed vias, wet or dry. This paper will discuss the materials and processes of these five major microvia formation methods. At the end, eight key manufacturers from Japan will be briefly illustrated for their research status and current capability of producing smallest microvia.
Predicting HDI design density
Authors: Holden Happy , Charbonneau Richard
Published: July 2002

This paper reveals a new methodology for predicting the most efficient design rules to follow for high density printed wiring boards prior to physical layout. The only input is from a schematic diagram, parts list and proposed board size. The methodology attempts toa prioridetermine the wiring capabilities of different PWB designs for a given product application. The particular focus is the difference between through‐hole and HDI designs.
Effect of Delamination on Moisture Accelerated Failures in Plastic Encapsulated Microcircuits
Authors: Pecht M. , Ranade Y. , Pecht J.
Published: July 2002

This paper presents a study to determine the extent to which delamination at the die to encapsulant interface affects the package moisture content, and electrical failures when subjected to unbiased temperature‐humidity testing. Moisture absorption experiments showed that the presence of delamination did not significantly after the measurable moisture absorption characteristics of packages. Reliability testing indicated that although delamination is generally thought of as a reliability risk, it may not be a sufficient condition to promote damage in packages under dormant storage conditions. Experimental results showed no parametric or functional failures (or visible degradation) in packages with 100% die surface delamination after 1000 hours of unbiased testing at 140°C/85%RH.
An overview of surface finishes and their role in printed circuit board solderability and solder joint performance
Authors: Vianco Paul T.
Published: July 2002

An overview has been presented on the topic of alternative surface finishes for package I/Os and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot‐dipped, plated, and plated‐and‐fused 100Sn and Sn‐Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all‐around best options in terms of solderability protection and wire bondability. Nickel/Pd finishes offer a slightly reduced level of performance in these areas which is most likely due to variable Pd surface conditions. It is necessary to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that include thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non‐Pb bearing solders are discussed.
Electric stress computation ‐ a needle‐plane electrode system with space charge effects
Authors: Chen G. , Davies A.E.
Published: July 2002

The electric stress profiles of a needle‐plane electrode system used in the laboratory for investigation of tree initiation and growth have been studied. Results from analytical solution based on a hyperboloid shaped needle tend to differ from those from experiments. One reason is that in practice it is difficult to produce a needle of such a shape. Moreover, researchers have used various shaped needles for their tests. Presents the effects of these needle parameters on the electric stress profile. To simulate the presence of space charge, examines two models, i.e. spherical and cylindrical regions around the tip. For simplicity, the space charge was assumed to be uniformly distributed in the confined region. Results show that space charges can enhance or reduce the electric stress adjacent to the needle tip depending on the nature of the applied voltage.
Self‐organisation in artificial neural nets
Authors: Andrew Alex M.
Published: July 2002

The usefulness of artificial neural nets stems from their ability to self‐adjust, or in some sense “learn”. In modern studies, the emphasis on powerful self‐organisation is less strong, but the early viewpoint is defended here as potentially useful. Possible extension of neural net capability to “symbolic” processing is related to Minsky’s “heuristic connection” and to Pask’s view of learning as necessarily involving reformulation of information in a new language. Relevance is demonstrated to the “Boxes” scheme of Michie and Chambers and recent developments in reinforcement learning.
Examining the generalizability of a leadership model: issues for assessing administrator performance
Authors: Marcoulides George A. , Larsen Terry J. , Heck Ronald H.
Published: July 2002

Recent demands for educational accountability and restructuring of schools in the United States have been directed at holding principals accountable for school outcomes. Unfortunately, although the number of states that mandate formal evaluation of principals has increased dramatically over the past several years, the quality of the assessments has not substantially improved. The study of principal assessment, therefore, has been slow to develop, has not experienced a high degree of systematization and has not been guided by firmly established theoretical considerations. Examines the generalizability of a leadership model using data from a recently completed study, and considers the use of this model in the development of a performance‐based evaluation approach to principal assessment.
Effects of stay‐back on teachers’ professional commitment
Authors: Hung Antia , Liu James
Published: July 2002

This study investigated the effects of stay‐back on teachers’ professional commitment, in order to develop an effective means to measure teachers’ commitment to the teaching profession which, according to various studies, contributes to “quality education”. Other possible factors, such as age, gender, marital status, tenure, educational level and position, were also studied. Suggestions on ways to increase commitment, based on the statistical findings, were also made. The results of causal‐comparative, correlation and multiple regression analyses revealed that stay‐back was the one factor which was found to be the most highly and significantly related to commitment. Apart from educational stay‐back, marital status, age and tenure were also proved to relate significantly to commitment. In this research, the accuracy and reliability of the stay‐back data were improved through adjustment for a secondary analysis.
Novel techniques for electronic component removal
Authors: Stennett A.D. , Whalley D.C.
Published: July 2002

Component removal for rework and repair is traditionally achieved by re‐melting of the solder, but the exposure of the assembly or its component parts to repeated soldering/ desoldering cycles may cause both immediate damage and create a significant long term reliability hazard. Rework is labour intensive and requires skilled operators. Area array components further increase the complexity of the rework process because of the number and inaccessibility of the solder joints. There is a growing requirement to recycle/reclaim electronic waste, creating the need for an effective process for dismantling of printed circuit board assemblies (PCBAs). This paper will present a brief review of alternative non‐thermal techniques for rework or dismantling of conventional soldered assemblies, including both chemical etchants and mechanical techniques. Results will then be presented on trials of chemical etchants, where rates of solder removal consistent with realistic times for component removal have been readily achieved using commercially available tin‐lead strippers. Electrochemical techniques are also shown to be usable in specific applications, i.e. where electrical contact can be readily made to the solder joints to be removed, and have the advantage of reclaiming the removed solder directly from the electrolyte.
Students as a central concern
Authors: Silins Halia C. , Murray‐Harvey Rosalind
Published: July 2002

Recent preliminary research in secondary schools suggests that indicators other than the traditional performance outcome measures of school achievement can be used to differentiate between school performance. These indicators are student factors that have been associated with accepted notions of quality schooling outcomes, such as student attitude to school, their approaches to learning and their academic self‐concept. This study examined student survey data collected from 30 schools in rural and metropolitan South Australia, including independent and public schools. The nature and strength of the relationships between student factors and selected school variables were tested against a range of school outcome measures such as school retention, academic results and SACE (certification) completion. The implications of these results for the kind of teaching and learning environment that promotes valued school outcomes is explicated and discussed.
The contexts of partial truths: an analysis of principal’s discourse
Authors: Bogotch Ira E. , Roy Cynthia B.
Published: July 2002

Using sociolinguistic methods and ethnography, looks at the continuous and in process relationship between everyday talk and school leadership. Through close discourse analysis of three distinct situations, demonstrates how administrative talk shapes and is shaped by a school’s contexts, creating constant possibilities for educational leaders. Discusses implications for understanding how and why moral leadership is tenuous and problematic using Dewey’s notion of mortality as the nurturing of educational ideas: that is, in practice, moral leadership is not always reflexive or progressive.
What makes a good senior secondary school?
Authors: Silins Halia C. , Murray‐Harvey Rosalind
Published: July 2002

Identifies characteristics of good senior secondary schools when defined as those providing post‐school options for students. The most successful schools were found to be the larger independent girls’ schools with predominantly transformational leadership practices that promoted positive teacher perceptions of school organisation and of students’ learning, attitudes, and school involvement. Path analysis was used to test a model of school effectiveness involving seven variables: sector, type size, and teacher views of leadership effects, school and student effects. The impact on school performance of school leadership and teachers’ strong sense of involvement in curriculum planning, teacher development and school culture was indirect and mediated through teachers’ assessment of students’ participation in learning and students’ attitudes to school. Raises issues about the purposes of schooling and the appropriateness of selected outcome measures as a basis for judging what makes a good school.
Implementation of shared governance for instructional improvement: principals’ perspectives
Authors: Blase Jo , Blase Joseph
Published: July 2002

Describes the practices, thoughts, and feelings of shared‐governance principals as they confront the challenges of school restructuring. The focus is on the principals’ perspective on shared governance and democratic schooling; the challenges of becoming involved in collaborative decision making with teachers, parents, and students; and the principals’ own professional growth as they strove to become “one among equals” with their colleagues. The data discussed here were drawn from a qualitative study of principals in nine schools affiliated with Glickman’s League of Professional Schools in Georgia. A protocol of open‐ended interview questions designed by the researchers, according to general guidelines for grounded theory inquiry, provided principals with the opportunity to identify and describe in detail their perspective on shared governance leadership in schools. Inductive analysis of the data generated a description of the implementation of shared governance that includes five salient themes: meanings, becoming involved, letting go of power, supportive processes, and supportive structures. Discusses findings in terms of the relevant empirical and theoretical literature.
Electronic commerce to support construction design and supply‐chain management: a research note
Authors: Elliman Tony , Orange Graham
Published: July 2002

Looks at the changing nature of the construction supply industry and the role of electronic commerce in the evolved market. With the emphasis shifting from supply‐ to demand‐driven product design, the trading relationships become more complex. In their current form, electronic commerce and brokering systems are too immature to support such relationships. Proposes an electronic market in design and supply capability that spans the supply chain and discusses some of the research issues raised by such a prospect. Many elements of a technical solution are available. The research must address significant changes in working practices and soft systems methods addressing human issues, which are more important than technological design. Exploration of business process re‐engineering options using simulation models is another important aspect of the work. Although the target area is the construction industry, many of the issues which will need to be explored are relevant for other sectors moving to adopt open networked solutions.
The development of B2C e‐commerce in Greece: current situation and future potential
Authors: Kardaras Dimitris , Papathanassiou Eleutherios
Published: July 2002

The development of Internet applications for business use is expected to change the way organisations operate, and improve their customer services. However, the potential of the Internet to improve customer satisfaction has not been studied, either in countries with well‐developed electronic markets or in countries in the early stages of e‐commerce. This article reports on the results of a survey of 120 companies in Greece. The aim of this study was to evaluate the potential of customer‐oriented Internet applications and to investigate how the Internet and e‐commerce can offer new opportunities for businesses to improve their customers’ satisfaction.
Facilitating designer‐customer communication in the World Wide Web
Authors: Tuikka Tuomo , Salmela Marko
Published: July 2002

Introduces a way to design geographically distributed virtual prototyping, a new Internet technology, in order to facilitate designer‐customer communication in the product development of small electronic devices, such as mobile telephones. First, we will present our research in the concept design domain with a set of requirements focusing on communication between the designer and the customer. Second, a technique called “smart virtual prototyping” will be presented to elaborate on the virtual prototyping techniques to be used over the World Wide Web. Third, we will present the main ideas, architecture and selected software techniques of WebShaman, which is an application built to demonstrate how a distributed virtual prototyping system could support geographically distant designer‐customer communication. Finally, we discuss the possible impact of the distributed virtual prototyping approach on the WWW community.
Security aspects of an enterprise‐wide network architecture
Authors: Loew Robert , Stengel Ingo , Bleimann Udo , McDonald Aidan
Published: July 2002

Two main areas of activity can be identified in the field of network security: the local area network and the common point between networks. Presents an overview of two projects concerning the above‐mentioned areas. While the first will concern security architectures based on active firewall components, the second presents a secure intranet solution. The combination of active firewall components with the DMZ concept can translate a security policy into reality and will result in a high level security firewall system. One of the most important security problems in an intranet is to ensure that every user has access only to the information which is relevant for his/her work. In our project this is solved using role‐dependent information access for each user.
Mobile access to the Internet: a mediator‐based solution
Authors: Alanko Timo , Kojo Markku , Liljeberg Mika , Raatikainen Kimmo
Published: July 2002

Nomadicity is a new challenge for computing and communication technologies. Modern cellular telephone systems extend the usability of portable personal computers enormously. A nomadic user can be given ubiquitous access to remote information stores and computing services. However, the behaviour of wireless links creates severe inconveniences within the traditional data communication paradigm. In this paper we give an overview of the problems related to wireless mobility. We also present a new software architecture for mastering the problems and discuss a new paradigm for designing mobile distributed applications. The key idea in the architecture is to place a mediator, a distributed intelligent agent, between the mobile node and the wireline network.
Intellectual capital in valuing intangible assets
Authors: Kennedy Frances
Published: July 2002

Knowledge companies who generate their revenue from leveraging the talents and contacts of professionals are confronted with two dilemmas ‐ acquiring institutional funding without hard collateral and managing these revenue‐generating talents. These companies appear to have understated balance sheets. Their value, however, can be highly appreciated as is illustrated by the stock prices. This presents a problem when acquiring institutional funding since hard collateral is scarce. Another dilemma is how to manage these revenue‐generating talents and systems. It appears that both external and internal sources have a need to measure, manage and grow these assets. This paper presents methods currently in use to identify and measure intangible assets and also experiments by applying five of these measurements to a single company over a period of eleven years. The purpose of this exercise is to note any similarities with financial measures and to determine the predictability of performance based on these indicators.
Organisational learning: “live” case studies and the consulting process
Authors: McKenna Steve
Published: July 2002

This paper describes and evaluates the use of two methods of case analysis in the conduct of “live” case studies undertaken by MBA students as part of their curriculum. Five small New Zealand businesses were involved and teams of students had to use a “Harvard” or “Western” approach. The paper proposes that in a rapidly changing and complex business environment, with significant emphasis placed on “learning”, the dialectical “Harvard” type approach facilitates much more effectively the development of organisational learning in small businesses. The paper outlines the issues involved in the use of both methods in “live” cases. It also suggests that “live” cases should be an integral part of all MBA curricula.
Smoothing STL files by Max‐Fit biarc curves for rapid prototyping
Authors: Koc Bahattin , Ma Yawei , Lee Yuan‐Shin
Published: July 2002

Presents a method ofMax‐Fitbiarc curve fitting technique to improve the accuracy of STL files and to reduce the file size for rapid prototyping. STL file has been widely accepted as ade factostandard file format for the rapid prototyping industry. However, STL format is an approximated representation of a true solid/surface model, and a huge amount of STL data is needed to provide sufficient accuracy for rapid prototyping. Presents aMax‐Fitbiarc curve fitting technique to reconstruct STL slicing data for rapid prototyping. TheMax‐Fitalgorithm progresses through the STL slicing intersection points to find the most efficient biarc curve fitting, while improving the accuracy. Our results show that the proposed biarc curve‐fitting technique can significantly improve the accuracy of poorly generated STL files by smoothing the intersection points for rapid prototyping. Therefore, less strict requirements (i.e. loose triangle tolerances) can be used while generating the STL files.