bluuebunny/crossref_metadata_2025 huggingface dataset:
A variational model for a symmetric transonic aerofoil
Authors: He Ji‐Huan
Published: August 2003

By the semi‐inverse method proposed by He, a variational principle is established for steady flow over a thin, symmetric, non‐lifting aerofoil. The nonlinear, small‐disturbance, velocity‐potential equation is obtained by minimizing the obtained functional, and all boundary conditions are converted into natural boundary conditions, resulting in much convenience when incorporating the finite element method.
Serendipity and information seeking: an empirical study
Authors: Foster Allen , Ford Nigel
Published: August 2003

“Serendipity” has both a classical origin in literature and a more modern manifestation where it is found in the descriptions of the problem solving and knowledge acquisition of humanities and science scholars. Studies of information retrieval and information seeking have also discussed the utility of the notion of serendipity. Some have implied that it may be stimulated, or that certain people may “encounter” serendipitous information more than others. All to some extent accept the classical definition of serendipity as a “fortuitous” accident. The analysis presented here is part of a larger study concerning the information‐seeking behaviour of interdisciplinary scholars. This paper considers the nature of serendipity in information‐seeking contexts, and reinterprets the notion of serendipity as a phenomenon arising from both conditions and strategies – as both a purposive and a non‐purposive component of information seeking and related knowledge acquisition.
New water soluble EP additive for environment friendly fluids
Authors: Domingues Dos Santos Fabrice , Guillemet Francois
Published: August 2003

Synthetic and semi‐synthetic fluids are known to be less sensitive to bacterial growth than soluble oils. However they often offer poor lubricating properties, especially in the extreme pressure (EP) regime. In this paper, we introduce an innovative sulfur based additive demonstrating outstanding EP performances despite being completely water soluble. In combination with oiliness and anti‐wear agents, such as phosphate esters or alkyl thio acids, it exhibits a wide range of lubricating properties which are requested for multifunctional lubricants. Finally, we show that synthetic and semi‐synthetic fluids containing this type of additive can be considered for severe metalworking operations.
Contracting out of a public library service: business to be, or not to be?
Authors: Harrington Keith
Published: August 2003

Evaluates a proposal by Invercargill City Council to contract out the Invercargill City Libraries to, initially, the present library manager. The reasoning of a move from the traditional form of public library governance is discussed, as well as the advantages and disadvantages of a library service being provided by a private company. The purpose of the paper is not to advocate contracting out but provides information to stimulate debate and add to the limited published research that exists in New Zealand and overseas.
A framework with a fragile foundation: thoughts from a critical friend on Framework for the Future
Authors: Usherwood Bob
Published: August 2003

Describes and critiques a report published by the UK’s Department of Culture, Media and Sport in 2003 which sets out a structure whereby public libraries will provide socially inclusive services and how this will be achieved. The report indicates that the modern mission of public libraries should be based on evolution, public value, distinctiveness and local interpretations of national programmes. New roles should emerge from traditional core skills, and focus on areas where public intervention will deliver large benefits for society.
Developing research skills in library and information science studies
Authors: Juznic Primoz , Urbanija Joze
Published: August 2003

Examines the role of research skills from the perspective of staff and students involved in courses at the Department of Library and Information Science and Book Studies, Faculty of Arts, University of Ljubljana. Library and information science programmes are expected to provide students with the right skills to become information specialists. The focus is on one narrow area of these skills, the research skills, i.e. research problem definition, research methods use and research report writing. Some of the students, as future professionals, will seldom have to conduct research, but will constantly have to read and evaluate it for their professional use. The analysis of the curriculum for the research content is presented. A publishable manuscript is a requirement for graduation at the Department of Library and Information Science and Book Studies. The dissertation should reflect the research skills acquired through the studies. This paper is actually a case study, but with the aim of presenting a possible solution on how to define research skills based on this study.
The humanoid robot scene in Japan
Authors: Kusuda Yoshihiro
Published: August 2003

Since the advent of Honda’s ASIMO and Sony’s AIBO, robot fever has broken out in the general public of Japan. However no significant business has yet materialized, except in the pet robot business in the toy industry. On the other hand serious basic research for humanoid robots is going on which may have an impact on the future of robotics. This report describes the current status of Japanese humanoid fever and its reality.
PathFinder image guided robot for neurosurgery
Authors: Finlay Patrick A. , Morgan Paul
Published: August 2003

This paper discusses the benefits that arise from the use of a robot arm for guiding neurosurgical operations. The design and operation of the PathFinder, safety issues and the accuracies that can be obtained and the use of a robot held camera for system calibration are described.
Do Dühring’s tribulations have any lessons for us today?
Authors: Senn Peter R.
Published: August 2003

This is an article about the possible lessons for academic freedom that Dühring’s expulsion from the University of Berlin might have for us today. It begins with a brief discussion of his strange fate in the English language literature in contrast with his high position in the history of economic thought. It is no surprise that questions of the denial of academic freedom have long been discussed. The remainder of the article is devoted to a discussion of academic freedom since his time and the possible lessons these developments might have for us today. The most important of these is the ancient truism – academic freedom is always under attack from many sides and must be vigorously defended.
Application of design of experiments to a spot welding process
Authors: Rowlands Hefin , Antony Jiju
Published: August 2003

Design of experiments (DOE) is a scientific method for identifying the critical parameters associated with a process and thereby determining the optimal settings for these process parameters for enhanced performance and capability. It is a powerful technique employed in the improvement phase of the Six Sigma methodology as a means to improve process yield, stability, customer satisfaction and reduce process variability which results in high scrap, rework and warranty costs. This paper presents the application of DOE to a spot welding process in order to discover the key process parameters, which influence the tensile strength of welded joints. Statistical analysis was carried out to identify the process parameters, which affect the mean strength and variability in weld strength. The results of the study encouraged the engineering team within the company to extend the application of DOE to other core processes within the business as a process performance improvement technique.
Issues in developing, managing and marketing electronic journals collections
Authors: Ashcroft Linda
Published: August 2003

The provision of electronic journals collections has required libraries and librarians to adapt and develop services and working practices. Research carried out at Liverpool John Moores University investigated promotion and evaluation of e‐journals in academic library collections in the UK and North America. Further issues discussed include cost implications and best value. Faced with many alternatives of packages and bundles, the questions of relevancy and management costs arise. The research also considered the prevalence and benefits of purchasing consortia. Promotion and evaluation of e‐journals are examined in light of changing user expectations, possible benefits from the supply chain and management skills in a changing collection environment.
The Platinum Web: sites dedicated to senior citizens on the Internet
Authors: Laurich Rob
Published: August 2003

With the continued growth of senior citizen usage of the Internet, the special needs of this user group have become identified and Web sites are being specifically marketed toward them. Since libraries have been identified as a major provider of Internet services for this group, it is important that librarians be aware of the unique Web sites for the older adult. The Platinum Web is an annotated bibliography of the most significant Web sites dedicated to the older user.
Multi‐tip sparker for the generation of acoustic pulses
Authors: Rutgers Wijnand R. , de Jong Ivan
Published: August 2003

Sparkers can be used for the production of acoustic pulses as seismic source for sub‐bottom profiling in the sea. A multi‐tip (200‐800 tips) sparker has been developed, which makes high‐resolution seismic profiling possible in deep water. The characteristics of the multi‐tip sparker system have been measured in a basin in the laboratory using different arrangements of the capacitive energy storage and salinity of the water. A model in Matlab is used to calculate the current waveform in the spark array for different layouts of the power supply.
Metadata mayhem: cataloguing electronic resources in the National Library of New Zealand
Authors: Todd Chris
Published: August 2003

This paper takes a chronological approach to the cataloguing of electronic resources within the National Library of New Zealand. It briefly outlines the early work in this area and then looks at how the role of a national library affects the cataloguing process. This is followed by a description of current approaches to cataloguing published digital materials and the transformation of the catalogue record that has been part of this process. Finally some issues that are still under discussion are outlined.
The digital divide: a global and national call to action
Authors: Cullen Rowena
Published: August 2003

The phrase “digital divide” has been applied to the gap that exists in most countries between those with ready access to the tools of information and communication technologies (ICTs), and those without such access or skills. This may be because of socio‐economic or geographical factors, educational, attitudinal and generational factors, or because of physical disabilities. The paper reviews recent research concerning the digital divide in New Zealand, and the factors that alienate people from enjoying the benefits of information technology and participation in the knowledge economy. While socio‐economic factors affect use of ICTs by urban Maori and Pacific Island communities, and rural communities are affected by inadequate telecommunications infrastructure, rural Maori are even more disadvantaged. The paper examines strategies used in the USA and the UK at national and regional levels to address similar issues, including the use of libraries to reduce the digital divide, and compares these with New Zealand initiatives, to identify positive means of increasing participation in the knowledge economy.
Changes in UK copyright law: implications for document delivery
Authors: Watkins Judy
Published: August 2003

Discusses some of the proposed changes to UK copyright law based on the Consultation Document issued in August 2002 which is intended to implement a recent EU (European Union) Directive. One of the biggest changes is the removal of any copying without permission for commercial purposes. Although there is no definition of “commercial” the Directive does state that it refers to an action that is directly or indirectly income generating. This will result in many customers having to pay copyright fees where in the past they have been able to obtain copies without any permission or fee. There will also be many cases where it is not clear whether or not the activity would or would not count as commercial. Libraries will need to ensure that their customers are educated and that their services are compliant with the new legislation. This will often require libraries to purchase a licence to allow them to continue to provide copies to all their customers.
Applying Quality Function Deployment to environmentally conscious design
Authors: Masui Keijiro , Sakao Tomohiko , Kobayashi Mitsuru , Inaba Atsushi
Published: August 2003

Presents a methodology for applying Quality Function Deployment (QFD) for environmentally conscious design in the early stage of product development. This methodology has been developed by incorporating environmental aspects into QFD to handle the environmental and traditional product quality requirements simultaneously. The “QFD for environment (QFDE)” proposed consists of four phases. Designers can find out which parts are the most important in enhancing environmental consciousness of their products by executing QFDE phase I and phase II. Further, a methodology is developed to evaluate the effects of design improvement on environmental quality requirements as phases III and IV. The results obtained from the case study of IC package show that QFDE could be applicable in the early stage of assembled product design, because the most important component from the viewpoint of the environment is clearly identified and multiple options for design improvement are effectively evaluated.
Strategic management by business metrics
Authors: Fehlmann Thomas M.
Published: August 2003

Applications of comprehensive Quality Function Deployment (QFD) – or QFD in the broad sense – to strategic management have been known for some time, and its results have been discussed within the international community of QFD specialists. It is therefore tempting to investigate the contribution of combinatory metrics to strategy deployment. Combinatory metrics are constructed upon the capability of QFD to evaluate the deployment topics’ contribution to customers’ needs. They provide a practical means to explain business strategy by “local” metrics that are easily understood and applied by responsible people. Combinatory metrics also point to foundations of QFD that explain how to apply QFD for very complicated environments. This foundation provides techniques and means to work with various influencing factors and conflicting topics. This paper explains the theory as needed for strategy deployment and presents a sample case from a software company.
Evaluating opportunities for expanded information access: a study of the accessibility of four online databases
Authors: Horwath Jennifer
Published: August 2003

The author presents the results of a survey conducted for the purpose of evaluating the accessibility of four proprietary Web‐based online resources: EBSCOhost MasterFile Elite, Electric Library Plus, Encyclopaedia Britannica Online, and The Oxford English Dictionary Online. The survey respondents were computer users who are blind or visually impaired and were already comfortable with using the World Wide Web. The survey was conducted entirely via e‐mail. The survey responses reveal which online resources are accessible but also the elements that comprise an accessible online resource are described. This information can be used as a guide when evaluating other online resources.
Social action research and small hospitality firms
Authors: Di Domenico MariaLaura , Morrison Alison
Published: August 2003

Develops a conceptual framework for qualitative research directed at small hospitality firms, ensuring an appropriate “fit” between theory, research and analysis, and aiding subsequent practical applications for hospitality research practitioners. Proposes that certain key theoretical and qualitative research issues are often absent from hospitality research. This is to the detriment of the development of the subject area. Investigates justification, implications for choice, and application of methodologies. This serves to explore the relevance of one central school of social scientific thought, the action/interaction approach, to the multidisciplinary hospitality field of study. Shows how this model fits in with a research approach which takes the point of view of the subject or respondent. The overall aim is to debate the utility of this orientation for small hospitality firm research in contrast to the more commonly taken structural or organisational analysis. Examples are drawn from a specific empirical research enquiry to illustrate how conceptual and practical challenges of concern to critics of this approach are resolved in the field.
Towards better qualitative performance measurement in organizations
Authors: Yih‐Tong Sun Peter , Scott John L.
Published: August 2003

In a rapidly changing business environment, the need to constantly adapt is deemed essential to maintain competitive advantage. This requires an optimum balance of quantitative and qualitative measures to monitor progress and performance. This paper provides a framework of thought process that will guide practitioners in developing better qualitative measures and seeks to answer three essential questions: thought process 1 – what is the nature of reality? Provides the answer to the question, can the phenomenon be realistically measured? Thought process 2 – what are the processes used for constructing the measure? Provides answer to the question, are the processes appropriate and sufficiently influential? Thought process 3 – what usefulness and power does this measure provide? Provides answer to the question, is it powerful in a practical environment? The framework was applied to measurement in learning organization contexts and ten models were reviewed. Conclusions cover deficiencies in the models and suggestions on how they might be improved.
Scenario planning after 9/11: managing the impact of a catastrophic event
Authors: Kennedy Peter , Perrottet Charles , Thomas Charles
Published: August 2003

Managers need a framework for assessing various kinds of risk and uncertainty that will continue to confront corporate decision makers as the 9/11 event plays out over the following months and years. The authors suggest an innovative scenario process, one that provides business continuity planning and medium‐term operational planning with a more rigorous analytical grounding, but without overburdening the process with excessive and ultimately counter‐productive complexity. The authors have introduced alternative scenario‐based tools to respond to this specific need for continuity assurance and near‐term operations planning. Case one: business continuity planning (BCP) for the management of one leading global financial services firm committed to a process of identifying and remedying gaps in the recoverability of its key assets. Workshops developed strategies that would close unacceptable asset recovery gaps in two scenarios. Case two: medium term operational planning for a professional services firm in the weeks that followed 9/11 evaluated the plausible range of impacts on their business and operations as the USA and the world took action and terrorist groups responded further. Case three: three years ago the US Coast Guard developed scenarios for very long range strategic planning for their long view project. The Coast Guard developed ten basic strategies from these scenarios. The fourth strategy was “Acquire full maritime domain awareness”. The goal was to give the Coast Guard the ability to acquire, track, and identify in real time any vessel or aircraft entering America’s maritime domain. Maritime domain awareness (MDA) turned out to be highly relevant for USCG decision making both before and after 9/11. Of all the major US federal services involved in the 9/11 response operation, the Coast Guard was singled out for its agility and preparedness.
Metamorphosis in the auto industry
Authors: Benko Cathleen , McFarlan Warren
Published: August 2003

Globally the automotive industry is transforming itself. During this period of uncertainty and discontinuity, entirely new ways of doing business are emerging. Three trends stand out. Together, they represent a convergence of progressive thinking from the major players. Trend #1: The manufacturer’s changing relationship with its customers. Increasingly customers are being given the opportunity to customize their purchase, while the automakers are becoming more adroit at understanding which customers create the most value for them. The customer’s demand for speed of delivery plus the automaker’s desire to make only cars that customers want (so they won’t be stuck with inventories that must be sold at discount), have resulted in shrinking the “order to delivery” cycle. Another dimension is the fact that cars are evolving into electric appliances. Today, 22 percent of a car is electronic content. In ten years, that will be 40 percent. Connectivity will promote extended relationships with auto owners fostering a greater customer‐centric focus. Trend #2: New partnerships with suppliers. US automakers are becoming more like their Japanese and European competitors: they strive for cooperation and are purchasing entire subassemblies (such as doors or power trains) from suppliers. This is leading to radically new infrastructure to support design, procurement and logistical processes. By connecting with suppliers and sharing demand data, quality and responsiveness are improving and costs are being reduced.
Editorial
Authors: Alshawi Sarmad , Irani Zahir , Baldwin Lynne
Published: August 2003

Introduces the special issue. Focuses first on concepts of knowledge in knowledge management before discussing the importance and role of knowledge in learning and the learning organisation. Discusses the role of knowledge and learning with regard to organisational change and the challenges that this poses with regard to benchmarking. Focuses then on information and communication technologies and to the role that these play in the complexities of business organisational change. Concludes with a discussion of the importance of the human aspects before outlining the contribution of the seven papers which comprise this special issue.
Philosophy for managers?
Authors: Green Gillian D.
Published: August 2003

Ethics is attracting increasing attention in management of both public‐ and private‐sector organisations. For managers within health‐care systems, ethical issues can be most acute, especially given the human rights issues involved in new legislation. This paper explores some of the ways in which philosophy may potentially offer guidelines to managers faced with the need to make decisions ethically. It draws on a small number of philosophical perspectives to demonstrate how they can assist in informing ethical decision making, and illustrates its arguments through one topic, suicide prevention, an area of relevance to health managers but one that is beset by some of the most profound ethical dilemmas. The ways in which philosophy may assist in decision making in this one example are, it is argued, generalisable to many other health issues where complicated decisions have to be made. The paper develops a philosophical framework consisting of the ethical considerations of “self‐love”, “humanity”, “the value of human life” and “duty to others” and demonstrates, through the use of two hypothetical case studies, how these can be applied to a decision‐making process so as to reduce inconsistencies in attitudes and practice.
Characteristic Physical Parameter Approach to Modeling Chillers Suitable for Fault Detection, Diagnosis, and Evaluation
Authors: Jia Yongzhong , Reddy T. Agami
Published: August 2003

Model-based fault detection and diagnosis approaches based on statistical models for fault-free performance concurrently require a fault classifier database for diagnosis. On the other hand, a model with physical parameters would directly provide such diagnostic ability. In this paper, we propose a generic model development approach, called the characteristic parameter approach, which is suitable for large engineering systems that usually come equipped with numerous sensors. Such an approach is applied to large centrifugal chillers, which are generally the single most expensive piece of equipment in heating, ventilating, air-conditioning, and refrigeration systems. The basis of the characteristic parameter approach is to quantify the performance of each and every primary component of the chiller (the electrical motor, the compressor, the condenser heat exchanger, the evaporator heat exchanger, and the expansion device) by one or two performance parameters, the variation in magnitude of which is indicative of the health of that component. A hybrid inverse model is set up based on the theoretical standard refrigeration cycle in conjunction with statistically identified component models that correct for non-standard behavior of the characteristic parameters of the particular chiller. Such an approach has the advantage of using few physically meaningful parameters (as against using the numerous sensor data directly), which simplifies the detection phase while directly providing the needed diagnostic ability. Another advantage to this generic approach is that the identification of the correction models is simple and robust, since it requires regression rather than calibration. The entire methodology has been illustrated with actual monitored data from two centrifugal chillers (one a laboratory chiller and the other a field operated chiller). The sensitivity of this approach to sensor noise has also been investigated.
A Numerical and Experimental Study of Mass Transfer in the Artificial Kidney
Authors: Liao Zhijie , Poh Churn K. , Huang Zhongping , Hardy Peter A. , Clark William R. , Gao Dayong
Published: August 2003

To develop a more efficient and optimal artificial kidney, many experimental approaches have been used to study mass transfer inside, outside, and cross hollow fiber membranes with different kinds of membranes, solutes, and flow rates as parameters. However, these experimental approaches are expensive and time consuming. Numerical calculation and computer simulation is an effective way to study mass transfer in the artificial kidney, which can save substantial time and reduce experimental cost. This paper presents a new model to simulate mass transfer in artificial kidney by coupling together shell-side, lumen-side, and transmembrane flows. Darcy’s equations were employed to simulate shell-side flow, Navier-Stokes equations were employed to simulate lumen-side flow, and Kedem-Katchalsky equations were used to compute transmembrane flow. Numerical results agreed well with experimental results within 10% error. Numerical results showed the nonuniform distribution of flow and solute concentration in shell-side flow due to the entry/exit effect and Darcy permeability. In the shell side, the axial velocity in the periphery is higher than that in the center. This numerical model presented a clear insight view of mass transfer in an artificial kidney and may be used to help design an optimal artificial kidney and its operation conditions to improve hemodialysis.
Experimental/Analytical Analysis of Human Locomotion Using Bondgraphs
Authors: Pop Cristian , Khajepour Amir , Huissoon Jan P. , Patla Aftab E.
Published: August 2003

A new vectorial bondgraph approach for modeling and simulation of human locomotion is introduced. The vectorial bondgraph is applied to an eight-segment gait model to derive the equations of motion for studying ground reaction forces (GRFs) and centers of pressure (COPs) in single and double support phases of ground and treadmill walking. A phase detection technique and accompanying transition equation is proposed with which the GRFs and COPs may be calculated for the transitions from double-to-single and single-to-double support phases. Good agreement is found between model predictions and experimental data obtained from force plate measurements. The bondgraph modeling approach is shown to be both informative and adaptable, in the sense that the model resembles the human body structure, and that modeled body segments can be easily added or removed.
Effect of Thermal Damage and Biaxial Loading on the Optical Properties of a Collagenous Tissue
Authors: Jun J.-H. , Harris J. L. , Humphrey J. D. , Rastegar S.
Published: August 2003

Thermal denaturation can induce marked changes in the optical and mechanical properties of collagenous tissues. The optical properties are important in both therapeutic and diagnostic applications of lasers in medicine. Although mechanical stress can be caused by collagen shrinkage in laser-based therapies, how the mechanical loading state affects the optical properties is not well understood. We used a new computer-controlled biaxial testing system to subject bovine epicardium to various loading conditions both before and after multiple levels of thermal damage. An integrating sphere technique was used to measure transmittance and diffuse reflectance, from which absorption and scattering coefficients were calculated using a Monte Carlo method. Results showed that the scattering coefficient increased with increasing mechanical load but decreased as the degree of thermal damage increased. There was no significant change in the absorption coefficient due to thermal damage over the ranges studied.
Load Control Using Building Thermal Mass
Authors: Braun James E.
Published: August 2003

This paper provides an overview of research related to use of building thermal mass for shifting and reducing peak cooling loads in commercial buildings. The paper presents background on the concept and the problem of optimizing zone temperature setpoints and provides specific results that have been obtained through simulations, controlled laboratory testing, and field studies. The studies have demonstrated significant savings potential for use of building thermal mass in commercial buildings. However, the savings are sensitive to many factors, including utility rates, type of equipment, occupancy schedule, building construction, climate conditions, and control strategy. The paper also attempts to provide an assessment of the state of the art in load control using building thermal mass and to identify the steps necessary to achieve widespread application of appropriate control strategies.
An Overview of Artificial Intelligence-Based Methods for Building Energy Systems
Authors: Krarti Moncef
Published: August 2003

An overview of commonly used methodologies based on the artificial intelligence approach is provided with a special emphasis on neural networks, fuzzy logic, and genetic algorithms. A description of selected applications to building energy systems of AI approaches is outlined. In particular, methods using the artificial intelligence approach for the following applications are discussed: Prediction energy use for one building or a set of buildings (served by one utility), Modeling of building envelope heat transfer, Controlling central plants in buildings, and Fault detection and diagnostics for building energy systems.
Calculation of Stress Intensity Factors and Crack Opening Displacements for Cracks Subjected to Complex Stress Fields
Authors: Kiciak A. , Glinka G. , Burns D. J.
Published: August 2003

Fatigue cracks in shot peened and case hardened notched machine components and high-pressure vessels are subjected to the stress fields induced by the external load and the residual stress resulting from the surface treatment or autofrettage. Both stress fields are usually nonuniform and available handbook stress intensity factor solutions are in most cases unavailable for such configurations, especially in the case of two-dimensional surface breaking cracks such as semi-elliptical and quarter-elliptical cracks at notches. The method presented in the paper makes it possible to calculate stress intensity factors for such cracks and complex stress fields by using the generalized weight function technique. It is also shown that the generalized weight functions make it possible to calculate the crack opening displacement field often used in the determination of the critical load or the critical crack size.
Erosions and Their Effect on the Fatigue Life of Thick Walled, Autofrettaged, Pressurized Vessels
Authors: Levy C. , Perl M. , Ma Q.
Published: August 2003

This paper summarizes the results that have been found in evaluating the effect of erosions on thick walled, autofrettaged, pressurized, cracked vessels. The problem is solved numerically via the FEM method. Autofrettage, based on von Mises yield criterion, is simulated by thermal loading and stress intensity factors (SIF’s) are determined by the nodal displacement method. SIF’s were evaluated for a variety of relative crack depths a/t and crack ellipticities a/c emanating from the tip of the erosion of various geometries, namely, (a) semi-circular erosions of small relative depths of the cylinder’s wall thickness t; (b) arc erosions for several dimensionless radii of curvature r′/t; and (c) semi-elliptical erosions with ellipticities of d/h. Other parameters evaluated were, in the cases of finite erosions, the semi-erosion length to the semicrack length Le/c, the erosion angular spacing α, and the autofrettage level. First, we summarize the differences found between a vessel with one erosion and one with multiple erosions. We show that for full cylinder length erosions, the erosions tend to make smaller cracks more dangerous than larger cracks in fully autofrettaged vessels and that as the crack grows the stress intensity factor initially decreases. We then show that as the crack grows further, the effect is to increase the effective stress intensity factor (SIF) but also to practically void the existence of the erosion. We show further that lower levels of autofrettage will lead to higher effective SIF’s but that partially eroded cylinders (cylinders where erosions are a fraction of the cylinder length) lead to lower SIF’s. Affecting these values in all cases, of course, are the erosion geometry and depth as well as the crack geometry and depth.
Comparison of Methods for Calculating Stress Intensity Factors for the Thread of a Pressure Vessel Closure and of a Gun Breech Ring
Authors: Kendall David P.
Published: August 2003

Non-mandatory Appendix D of Section VIII, Division 3 of the ASME Boiler and Pressure Vessel Code provides a method for calculating the stress intensity factors for the region of a thread root of a threaded closure. This method involves calculation of the distribution of stress acting on a plane normal to the axis of the thread. This distribution is fitted with several different cubic equations for different regions and the coefficients of these cubic equations are entered into an equation to calculate the distribution of stress intensity factor for each region. The values of stress intensity factor for each region after the first one are shifted to obtain a continuous distribution. In a paper to be presented at the August 2002 ASME Pressure Vessel and Piping Conference (Kendall 2002) the author compared the stress intensity factors calculated by the above Code method with those determined by Neubrand and Burns, 1999, using a weight function method. In Kendall, 2002, the stress intensity factors for this same closure design were calculated using the Code method and also calculated using a proposed modification of this method. The results showed slightly better agreement for the proposed modification of the Code method. This paper will report the details of these calculation methods and the results from Kendall, 2002. It will also give a comparison of the stress intensity factor results of these methods for a thread of a typical gun breech ring, and a comparison of the calculated fatigue crack growth lives.
Application of holographic diffusers to improve light uniformity of source with carbon fiber cathodes
Authors: Baturin A. S. , Chadaev N. N. , Leshukov M. Yu. , Sheshin E. P. , Chakhovskoi A. G.
Published: August 2003

Numerous advantages of field emission cathodes of carbon materials such as reliability, high efficiency, long lifetime, and short switching time make them great candidates for vacuum electronics applications such as light sources, LCD backlights, and many others. However, because of field emission features of carbon emitters there exists an unevenness of light distribution on the phosphor screen in cathodoluminescent light sources. One of the methods of improving the light uniformity is the application of holographic light shaping diffusers. In the present work we have investigated a possibility to improve a brightness distribution in the cathodoluminescent light source with a carbon fiber cathode applying various holographic diffusers.
Study of micro-glow discharges as ion sources for ion mobility spectrometry
Authors: Longwitz Ralf G. , van Lintel Harald , Renaud Philippe
Published: August 2003

We develop a microionizer as the ion source in a miniaturized spectrometerlike gas analyzer, operating at atmospheric pressure. Several options for the ionizing principle were considered. The application of dc glow discharge in a microsystem was studied in detail and first devices were fabricated and tested. We obtained stable dc plasmas in micromachined electrode gaps from 1 to 50 μm width, at pressures up to 105 Pa in various gases. With 1 and 3 μm gaps, stable glow was achieved at atmospheric pressure in Ar and N2, respectively. In a macrosystem, we extracted ions from a dc glow discharge and controlled the ion flow with a grid.
Electron emission from nanotips of amorphous diamond
Authors: Kan M. C. , Huang J. L. , Sung J. C. , Lii D. F.
Published: August 2003

Amorphous diamond can be deposited with a high-density (4×1010 emitters/cm2) of nano-sized emitters. The turn on applied field strength was reduced by increasing aspect ratio of amorphous diamond nanotips. Moreover, the field emission was highly sensitive to the aspect ratio of tips, and relatively inert to the sp3/(sp3+sp2) ratio. The lowest turn on applied field strengths was 4.6 V/μm at the current density of 10 μA/cm2; and 11 V/μm at the current density of 10 mA/cm2. High reproducibility of field emission was also observed in this study.
Effect of substrate on the step coverage of plasma-enhanced chemical-vapor deposited tetraethylorthosilicate films
Authors: Lan Jin Kun , Wang Ying-Lang , Chao Chuen Guang , Lo Kuang-yao , Cheng Yi Lung
Published: August 2003

Plasma-enhanced chemical-vapor deposition tetraethylorthosilicate (TEOS) films are extensively used as the interlayer dielectric films in multilevel interconnection processes. When TEOS oxide films were deposited on metal patterns three different substrates, titanium nitride (TiN), aluminum (Al), and oxide (SiO2), were used. This study examines the dependence of these substrates on TEOS step coverage. The deposition rates of TEOS oxide revealed that the SiO2 substrate lead to highest TEOS deposition rate during the initial deposition period of 5 s. Then, the TEOS deposition rate of the substrates was nearly the same. The TiN substrate exhibited the highest sidewall step coverage but the sidewall step coverage of the Al substrate deteriorated due to its granular surface. Additionally, different substrates exhibited different coverage of the bottom step. Moreover, the bottom step coverage exceeded the sidewall coverage for all substrates.
Fabrication of controlled sidewall angles in thin films using isotropic etches
Authors: Ponoth Shom S. , Agarwal Navnit T. , Persans Peter D. , Plawsky Joel L.
Published: August 2003

Angular structures in thin films have applications in microelectronics and optoelectronics. In this study we analyze isotropic etching of a two-layer system for the fabrication of angular sidewalls. Such a process is attractive because of its bulk processing capability. The isotropic etch process is demonstrated to provide good control of the sidewall angle. Theoretical analysis along with numerical simulation of the slope etching process is used to understand profile evolution. The numerical simulations showed that to obtain a flat angular sidewall face, reaction controlled etching is needed. Angular sidewalls are fabricated in plasma enhanced chemical vapor deposition (PECVD) silicon oxide with PECVD silicon nitride as the sacrificial layer using an isotropic, buffered hydrofluoric acid based, wet chemical etch. PECVD silicon nitride is shown to be a good material for use as the sacrificial layer because of its etch rate controllability through deposition conditions. Controlled angles ranging from 5° to 50° are demonstrated using this isotropic etch technique. Penetration of the etchant between the photoresist and the sacrificial silicon nitride layers is determined to be the cause of the limited range of the angles that could be etched. The rms roughness of the etched faces ranged from 79 to 389 Å.
Fabrication and characteristics of lateral type GaN field-emission arrays using metalorganic chemical vapor deposition
Authors: Lee Jae-Hoon , Lee Myoung-Bok , Hahm Sung-Ho , Lee Jung-Hee , Kim Jin-Sup , Choi Kyu-Man , Kim Yeo-Hwan
Published: August 2003

Lateral type GaN field-emission diodes were fabricated by metalorganic chemical vapor deposition. In forming the pattern, two kinds of procedures were proposed: a selective etching method with electron cyclotron resonance-reactive ion etching (ECR-RIE) or a simple selective growth utilizing Si3N4 film as the masking layer. The device fabricated using ECR-RIE exhibited electrical characteristics such as a turn-on voltage of 35 V for a 7 μm gap and an emission current of ∼580 nA/10 tips at an anode-to-cathode voltage of 100 V. The field emission characteristics of GaN tips were attributed to the tip structure, low electron affinity and short distance between the cathode and anode tips.
Stable field emission from W tips in poor vacuum conditions
Authors: Tondare V. N. , van Druten N. J. , Hagen C. W. , Kruit P.
Published: August 2003

We report a stable field emission (FE) current from sharp tungsten (W) tips in relatively poor vacuum (up to 10−2 mbar) conditions. We use small tip–anode spacing to keep the extraction voltage low. A simple current regulator circuit, with a bandwidth of ∼1.6 kHz, was designed, which controls the voltage applied according to the emission current measured. Without a current regulator circuit, an uncleaned W tip in unbaked 6×10−7 mbar system pressure cannot emit stable FE current and short-term fluctuations at a few nA current were found to be more than 300%. The current regulator circuit improves the FE current stability dramatically. It was observed that at current level of ∼3.5 nA and regulation voltage of ∼120 V the short-term fluctuations in the current were ∼5% at 6×10−7 mbar unbaked system pressure. Subsequently, the system pressure was increased in steps up to 10−3 mbar of argon gas and it was observed that the current regulator circuit worked at almost the same efficiency. Around 10−2 mbar of Ar gas pressure larger short-term fluctuations started appearing and around 10−1 mbar of Ar gas pressure the current regulator circuit failed to regulate the current. In another experiment, at 10−3 mbar of Ar gas pressure, at ∼1.5 and 25 nA current levels long-term FE current stability was recorded. Our results show that the FE current stability in our experiments is much better than that reported in the literature with feedback on the tip–anode distance. This study may find applications in focused electron beam systems as well as in electron impact ion sources.
Effect of oxygen on field emission properties of ultrananocrystalline diamond-coated ungated Si tip arrays
Authors: Ding M. Q. , Auciello O. , Carlisle J. A. , Gruen D. M.
Published: August 2003

The effect of O2 exposure on field emission properties of ultrananocrystalline diamond (UNCD) coated ungated Si tip arrays is reported. The behavior of current degradation during O2 exposure and current recovery following evacuation of O2 strongly depended on the initial current/electric field applied to the emitters. At a low initial current of 50 μA/electric field of 5.8 V/μm, O2 exposure (1×10−7, 5×10−7, and 1×10−6 Torr) resulted in a rapid decrease in current in the beginning, followed by a slow decrease. The current made a strong recovery toward the original value when O2 was pumped out. With an increased initial current of 180 μA/electric field of 10.3 V/μm, the currents recovered only to a lesser extent after O2 was evacuated. At an even higher initial current of 930 μA/electric field of 20.5 V/μm, the current decreased steadily and finally stabilized after an exposure of 720 L with only 34% degradation. To explain these observations, we propose a hypothesis of oxygen interaction with the UNCD surface.
Virtual interface approximation model applied to spectroscopic ellipsometry for on-line composition determination of metalorganic chemical vapor deposition grown ternary nitrides
Authors: Bonanni A. , Schmidegg K. , Montaigne-Ramil A. , Sitter H. , Hingerl K. , Stifter D.
Published: August 2003

In situ spectroscopic ellipsometry measurements in the ultraviolet-visible spectral range were performed during metalorganic chemical vapor deposition of GaN and AlGaN layers on sapphire. At first, the initial GaN–sapphire interface formation has been characterized and the optical response of the nitride layers for temperatures up to 1200 °C has been recorded. The data were used as the basis for evaluating kinetic ellipsometry measurements performed during growth: an algorithm, based on the virtual interface approximation model, has been developed and implemented to determine the layer composition of AlGaN multilayer structures in real time.
Copper blocking ability of nitrogen-incorporated silicon oxide film
Authors: Takeda Ken-ichi , Ryuzaki Daisuke , Mine Toshiyuki , Hinode Kenji , Yoneyama Ryo
Published: August 2003

Silicon oxynitride films were deposited by plasma-enhanced chemical vapor deposition (PECVD) using nitrous oxide (N2O) and monosilane (SiH4) chemistry. A wide range of nitrogen concentrations (from 0 to 8 at. %) in silicon oxynitride film was successfully obtained by controlling PECVD deposition conditions (rf power and SiH4/N2O flow ratio). The dependence of time-dependent dielectric-breakdown (TDDB) lifetime of such films with a copper anode on these PECVD conditions can be basically explained as the nitrogen-concentration dependence of the dielectric-breakdown lifetime. Increasing the nitrogen content from zero to 6 at. % improved the TDDB lifetime of the film by about seven orders of magnitude at a TDDB test temperature of 140 °C. However, increasing the nitrogen concentration to over 6 at. % did not improve the TDDB lifetime; in fact, doing so degraded it.
Green’s function approach for transport calculation in a In0.53Ga0.47As/In0.52Al0.48As modulation-doped heterostructure
Authors: Vasileska D. , Prasad C. , Wieder H. H. , Ferry D. K.
Published: August 2003

The gate voltage dependence of the low-field electron mobility has been investigated in a In0.53Ga0.47As/In0.52Al0.48As modulation-doped heterostructure using a real-time Green’s function formalism. All scattering mechanisms relevant for this material system have been incorporated in the theoretical model, including alloy disorder scattering, Coulomb scattering from the ionized impurities in the buffer layer, acoustic phonon, and piezoelectric scattering. The simulation results for the subband structure suggest occupation of two subbands at VG=0 V. Good agreement is observed between the simulated sheet electron densities and the experimentally extracted ones from Hall and Shubnikov–de Haas oscillatory magnetoresistance measurements. The mobility results for the structure investigated suggest that alloy-disorder scattering is the dominant mobility degradation mechanism.