bluuebunny/crossref_metadata_2025 huggingface dataset:
Complexity analysis, uncertainty management and fuzzy dynamical systems
Authors: Dutta Majumder D. , Majumdar Kausik Kumar
Published: June 2004

In this paper, we present a brief study on various paradigms to tackle complexity or in other words manage uncertainty in the context of understanding science, society and nature. Fuzzy real numbers, fuzzy logic, possibility theory, probability theory, Dempster‐Shafer theory, artificial neural nets, neuro‐fuzzy, fractals and multifractals, etc. are some of the paradigms to help us to understand complex systems. We present a very detailed discussion on the mathematical theory of fuzzy dynamical system (FDS), which is the most fundamental theory from the point of view of evolution of any fuzzy system. We have made considerable extension of FDS in this paper, which has great practical value in studying some of the very complex systems in society and nature. The theories of fuzzy controllers, fuzzy pattern recognition and fuzzy computer vision are but some of the most prominent subclasses of FDS. We enunciate the concept of fuzzy differential inclusion (not equation) and fuzzy attractor. We attempt to present this theoretical framework to give an interpretation of cyclogenesis in atmospheric cybernetics as a case study. We also have presented a Dempster‐Shafer's evidence theoretic analysis and a classical probability theoretic analysis (from general system theoretic outlook) of carcinogenesis as other interesting case studies of bio‐cybernetics.
Using the Adomian method for solving a class of boundary differential systems
Authors: Benabidallah Mohamed , Cherruault Yves
Published: June 2004

In this study, the aim is to solve a class of boundary systems, using the Adomian decomposition method. This method gave very good results for solving algebraic, differential integral and partial differential equations.
The impact of structure and process attributes on satisfaction and behavioral intentions
Authors: Bendall‐Lyon Dawn , Powers Thomas L.
Published: June 2004

This paper develops a framework that links satisfaction with structure and process attributes to global satisfaction and behavioral intentions. The authors develop and present a structural equation model that encompasses these relationships based on a survey of 635 consumers of healthcare services. The results indicate that satisfaction with both structure and process attributes have a significant impact on global satisfaction. Global satisfaction was found to directly influence both intention to recommend and intention to return to the healthcare service provider.
The effects of organisational climate on market orientation: evidence from the facilities management industry
Authors: Nwankwo Sonny , Owusu‐Frimpong Nana , Ekwulugo Frances
Published: June 2004

Market orientation is widely held as a credo for organisational success. Essentially, this means that organisations that are market oriented tend to perform better than those that are not. As a result of this logic (i.e. market orientation‐performance link), scholars from a wide array of disciplines are showing an increasing interest in fleshing out the factors that determine organisational market orientation stances. Based on a sample drawn from the UK's facilities management industry, this paper examines the impact of organisational climate factors on market orientation stances of facilities management firms. The results reveal that organisational climate has a determinant influence on market orientation stances.
The impact of service failure severity on service recovery evaluations andpost‐recovery relationships
Authors: Weun Seungoog , Beatty Sharon E. , Jones Michael A.
Published: June 2004

Previous research has found that interactional justice and distributive justice are critical factors influencing customer satisfaction after a service recovery. In addition, previous service recovery research has found that satisfaction is an important determinant of key outcome variables such as trust, commitment, and negative word‐of‐mouth. The current study extends previous research by investigating the role of service failure severity within the existing framework of service recovery research. The results indicate that service failure severity has a significant influence on satisfaction, trust, commitment, and negative word‐of‐mouth. The results also provide partial support for a moderating influence of service failure severity. Implications and areas for future research are discussed.
The relative influence of organisational commitment and job satisfaction on service quality of customer‐contact employees in banking call centres
Authors: Malhotra Neeru , Mukherjee Avinandan
Published: June 2004

An inter‐disciplinary approach is adopted to provide a deeper understanding of the human resource‐service quality relationship. The paper tests the relationships organisational commitment and job satisfaction have with service quality of customer‐contact employees. Hypotheses are constructed by reviewing literature in the areas of human resource management and services marketing. A study comprising 342 employees was conducted in four telephone call centres of a major UK retail bank. Investigates how different forms of organisational commitment and job satisfaction influence the service quality delivered by contact employees. Findings indicate that job satisfaction and organisational commitment of employees have a significant impact on service quality delivered. The affective component of commitment was found to be more important than job satisfaction in determining service quality of customer‐contact employees.
Customer loyalty to content‐based Web sites: the case of an online health‐care service
Authors: Gummerus Johanna , Liljander Veronica , Pura Minna , van Riel Allard
Published: June 2004

Past e‐service research has largely concentrated on customer responses to online retailers. The present study sheds light on the determinants of customer loyalty to a content‐based service, a healthcare Web site. Content‐based service providers must build a loyal customer base in order to attract advertisers and sponsors. Lack of trust has been one of the most important reasons for consumers not adopting online services involving financial exchanges, but trust appears to be equally important to exchanges that require divulging sensitive information, such as health issues. Results reveal that loyalty to the health site is satisfaction‐driven, but that trust is the main antecedent of satisfaction. Need fulfilment, responsiveness, security and technical functionality of the Web site are shown to influence trust. Managerial implications are provided.
Retaining and divesting customers: an exploratory study of right customers, “at‐risk” right customers, and wrong customers
Authors: Woo Ka‐shing , Fock Henry K.Y.
Published: June 2004

The axiom that “the customer is always right” is no longer valid when companies realize that some of their customers are not right at all. Paying too much attention to these so‐called “wrong” customers may jeopardize a company's survival and profitability. Right customers have to be retained, “at‐risk” right customers have to be recovered, and wrong customers have to be divested. This study attempts to operationalize the concept of customer “rightness” and “wrongness” in terms of different configurations of attribute satisfaction and overall satisfaction. Based on the result of a discriminant analysis of satisfaction survey data, customers with different configurations of attribute satisfaction and overall satisfaction are re‐examined in terms of switching intention, behavioral patterns and demographic characteristics in order to highlight any significant descriptor.
An exploratory study of influences on retail service quality: a focus on Kuwait and Lebanon
Authors: Raven Peter , Welsh Dianne H.B.
Published: June 2004

The Middle East is a growing and lucrative marketplace. This exploratory study examines retail service in Kuwait and Lebanon, regions with long histories of trade. Retail service, however, has not been well documented in this region. As far as is known, this is the first study that examines customer and salespeople perceptions of service encounters in these countries in light of their culture, religion, and nationalities. As retailers expand into new markets worldwide, such information is vital to their success. Future research directions are discussed.
Consumer switching behavior in the Asian banking market
Authors: Gerrard Philip , Barton Cunningham J.
Published: June 2004

This study seeks to identify the types of incidents which cause consumers to switch between banks, the weighting of each incident on the switching decision, whether single or multiple incidents influence switching decisions, and the extent to which switchers explain the problems they have faced prior to exiting. The key findings show that bank switching is strongly influenced by three types of incident: service failures, pricing and inconvenience, with pricing being more influential. Seventy‐five percent of bank switching is caused by more than one incident, and some 7 percent of respondents said they had spoken to bank staff in the period before exiting. The implications of these findings are presented.
The structure of commitment in consumer‐retailer relationships
Authors: Sánchez Manuel , Angeles Iniesta M.
Published: June 2004

A comprehensive model of commitment in the context of consumer‐retailer relationships is developed in this study. It gives a careful description and theoretical justification of the different dimensions, which compose this construct. To check the reliability and validity of the scale of measurement proposed, the generation and purification of the measurement items is subjected to a rigorous process, aiming at testing the higher‐order structural model proposed in this paper. According to this model, commitment is composed of five final dimensions. The results confirm the outlined structure previously indicated in this study, obtaining a reliable and valid scale. Theoretical and managerial implications, limitations and future research directions are also discussed.
Personal control and coping with retail crowding
Authors: Dion Delphine
Published: June 2004

To provide high quality services under conditions of crowding, it is important to understand the relationships between crowding and personal control. Indeed, in recent years, there has been growing belief that personal control is significant in coping with crowding. However, most studies have been of limited theoretical and practical value because they did not provide an integrated conceptualization of crowding. The results of a field study demonstrate that the personal control‐crowding relationships depend on the individual's crowding experience and the nature of personal control.
Collaborative relationship bundling: a new angle on services marketing
Authors: Barrutia Legarreta José M. , Echebarria Miguel Carmen
Published: June 2004

This article proposes a new approach to bundling for both the marketing of services and relationship marketing. Reviews the literature on both bundling and relationship marketing and puts forward a new theoretical approach. Uses the case method as a means of defending the argument and justifies its use in this specific research project. Demonstrates that collaborative relationship bundling can constitute the strategic core of a company; at least, if the firm's primary goal is to maximise the opportunities of attracting valuable customers within competitive markets. Research bears out some results from previous studies, while it finds other results to be questionable. Shows that the strategic implications of bundling are only partially explained in terms of a price or product focus, which was what previous research had concentrated on. A specific price bundle can have more strategic implications than a different specific product bundle, due to the associative power of bundling and its interactive capacity. As an essential part of this approach, a company must define bundling through an in‐depth appraisal of the actual contextual experience of the customer, rather than focusing solely on reservation prices, which is where previous literature had laid its main emphasis. Calculates the lifetime value of the average customer attracted through bundling as compared to that of the average customer in the sector studied, and thus is able to demonstrate that the customer attracted through bundling is of greater value. The case method provides an in‐depth explanation but the results it provides may not necessarily be generalised into other contexts. Develops therefore a model to identify the factors that explain the success registered in the case selected for analysis. Puts forward 11 propositions suitable for comparative application in other contexts.
Market orientation, brand investment, new service development, market position and performance for service organisations
Authors: Matear Sheelagh , Gray Brendan J. , Garrett Tony
Published: June 2004

This paper investigates how three marketing‐related sources of advantage – market orientation, new service development and brand investment – contribute to service firm performance by operationalising the sources‐position‐performance framework in a multi‐sector sample of service organisations. New service development and brand investment are found to contribute to the attainment of positional advantage and thence to performance. Market orientation, when considered in combination with these other sources, does not contribute directly to positional advantage and performance. Cost, brand and new service success positions are found to contribute to service firm performance.
Online service quality dimensions and their relationships with satisfaction
Authors: Yang Zhilin , Fang Xiang
Published: June 2004

This exploratory research intends to extend our understanding of service quality and customer satisfaction within the setting of online securities brokerage services. Based upon conceptual frameworks from the areas of services marketing and information systems management, the authors uncovered 52 items across 16 major service quality dimensions by content analysis of 740 customer reviews. The results indicate that primary service quality dimensions leading to online customer satisfaction, with the exception of ease of use, are closely related to traditional services while key factors leading to dissatisfaction are tied to information systems quality. In addition, major drivers of satisfaction and dissatisfaction are identified at the sub‐dimensional level. Theoretical contribution and managerial implications of the findings are further discussed.
Benchmarking knowledge management in a public organisation in Malaysia
Authors: Omar Sharifuddin bin Syed‐Ikhsan Syed , Rowland Fytton
Published: June 2004

There is relatively very little information on knowledge management in the public sector, and even less in developing countries. This paper investigates and examines the availability of a knowledge management strategy in a public organisation in Malaysia. This paper also examines perceptions on the benefits, problems, responsibilities and technological aspects that are entailed in managing knowledge in an organisation. Issues that encourage and restrict knowledge generation and knowledge sharing are also discussed. To achieve an in‐depth study, the Ministry of Entrepreneur Development of Malaysia was chosen for a case study. A questionnaire was used as the main instrument in gathering data, and a total of 154 respondents were involved in the survey. Although the Ministry does not have any specific knowledge management strategy, the study reveals that knowledge in the Ministry was available in the Ministry's procedures and policies, job manual procedure, ISO 9002, desk file, work flow and databases.
Industry‐specific cycles and companies' financial performance comparison using self‐organizing maps
Authors: Länsiluoto Aapo , Eklund Tomas , Back Barbro , Vanharanta Hannu , Visa Ari
Published: June 2004

Multilevel environment analysis is important for companies operating on the global market. Previous studies have in general focused on one level at a time, but the need to perform multilevel environment analysis has also been stressed. Multilevel analysis can partly explain the benchmarking gap between companies, as changing conditions in the upper environment levels affect lower levels. In today's information‐rich era, it is difficult to conduct multilevel analysis without suitable computational tools. This paper illustrates how the self‐organizing map can be used for the simultaneous comparison of industry‐level changes and financial performance of pulp and paper companies. The study shows the importance of simultaneous analysis, as some simultaneous changes were found at both industry and corporate levels. Also found were some industry‐specific explanatory factors for good (Scandinavian companies) and poor (Japanese companies) financial performance. The results indicate that the self‐organizing map could be a suitable tool when the purpose is to visualize large masses of multilevel data from high‐dimensional databases.
Benchmarking design‐build procurement systems in construction
Authors: Lam Edmond W.M. , Chan Albert P.C. , Chan Daniel W.M.
Published: June 2004

Benchmarking can be an effective way of helping organizations to deliver better services through continuous improvement. The concept of benchmarking has been extensively applied to the construction industry in recent years to enhance the performance of the project delivery process. Success is hard to achieve, especially for a construction project delivered by an innovative procurement method – design and build, and the identification of critical success factors can enable project team leaders to make improvements in some particular areas. This paper aims to establish a conceptual framework of critical success factors (CSFs) for design‐build projects in construction. From the framework, it is hypothesized that project success of a design‐build project is a function of the interaction among project characteristics, project procedures, project management strategies, project‐related participants, project work atmosphere and project environment. The CSFs so identified can provide practitioners and academics with a better understanding of running a design‐build project successfully to develop a benchmark for the D&B project delivery process.
Cost income ratio benchmarking in banking: a case study
Authors: Hess Kurt , Francis Graham
Published: June 2004

This paper examines how ASB Bank, a New Zealand‐based retail bank, made use of cost income ratio benchmarking when reviewing its operational efficiency. In particular, it shows the difficulties associated with the benchmarking process in the sector and details the practical steps taken to obtain meaningful comparative information. It is interesting that, while the cost income ratio was the principal metric used in this benchmarking exercise, it sought to identify best practice not in terms of minimizing this ratio but rather in terms of identifying typical ratios and cost structures among successful banking institutions.
Benchmarking the port services: a customer oriented proposal
Authors: Cuadrado Manuel , Frasquet Marta , Cervera Amparo
Published: June 2004

In recent years, ports have experienced a period of significant growth and development along with intense inter‐port rivalry as a consequence of intermodality and hinterland development. It is therefore vital that port management bodies define and implement suitable strategies. This paper aims to adapt the benchmarking technique to the sphere of ports. Compares the activity of a port with that of its competitors, which is considered to be excellent. This is a strategic approach where consideration of the needs of the client, shipping lines and export‐import companies is the axis of the benchmarking process.
Living in an uncertain world
Authors: Pearson Ian
Published: June 2004

Discusses some of the changes that are affecting us today and in the future, and some of the ways in which people try to cope with them, hopefully putting us in a better position to work out the consequent changes resulting from the human stimulus/response cycle. Concludes that the telecommunications industry is both a cause and a solution to the problem of change.
Futures thinking to achieve sustainable development at local level in Ireland
Authors: Kelly Ruth , Sirr Lorcan , Ratcliffe John
Published: June 2004

We are living in times of unprecedented global change and upheaval and over the next ten to 20 years governments, organisations and individuals will face increasing difficulties in an environment of growing complexity, heightened uncertainty and a quickening pace of change. The concept of sustainable development implies the reconciliation of long‐term socio‐economic development, environmental protection and quality of life; essentially it is concerned with the future. Unfortunately, the potential for linking “futures thinking” to debates about sustainable development at local and regional government levels is relatively undeveloped, particularly in Ireland. Responding to this challenge, The Futures Academy at Dublin Institute of Technology, Ireland, was established in January 2003 to provide both a research and consultancy forum for future‐proofing policies and strategies using the “prospective through scenarios” methodology. This paper describes the evolution of sustainable development in Ireland and the generic field of futures thinking, with particular focus on the prospective process which may assist key local policy makers and stakeholders move towards sustainable development for future generations in Ireland.
Individual and organisational learning: a model for reform for public organisations
Authors: Jorgensen Bradley
Published: June 2004

Discusses how public sector organisations should respond to emerging social and demographic trends, the changing nature of work set against the context of globalisation, the knowledge economy and the influence of information and communication technologies. Argues that the new ways of doing things, which emphasise collaborative action and learning, mandates the adoption of a high performance governance model instead of “command‐based” management. Proposes an integrated parcel of workforce strategies that supports organisational change, addresses noted social and demographic trends, builds social and human capital, recognises the value of life‐long‐learning, accommodates the rise of Self, embraces flexibility and provides for quality employment and tailored opportunities for the public sector's diverse workforce as the preferred corporate policy option.
Enterprise skills and enterprise learning
Authors: Ward Anne
Published: June 2004

In an era marked by profound technological change young people must prepare for a future in which rapid innovation is accompanied by the passing of traditional social norms such as career paths and job security. This calls for a level of self‐reliance, self‐determination and preparedness for life‐long learning not required in previous generations. Traditional measures of academic success overlook the broader skill set that is needed for success in the new environment. Emotional intelligence and enterprise skills now form part of a fundamental skill set which has not been given prominence in a traditional school curriculum designed towards a job outcome. Young people need not be victims of change. Parents, educators and entrepreneurial role models in the wider community can all play a role in preparing young people for a life of purpose in which they are aware of and can draw on their talents and abilities.
American diplomacy revisited: is “military tourism” essential?
Authors: Richardson Jacques
Published: June 2004

The US foreign service was a civilian process until the end of the Second World War. Since then, the armed forces have encroached on the State Department's diplomatic mission. The Goldwater‐Nichols Act of 1986 authorized worldwide “Commands” in the Department of Defense. This left to the uniformed heads of the Commands the latitude – and funds – to usurp more of the diplomats’ foreign‐affairs authority within their geographic areas. It is time to change this strategy.
Stimulating and evolving knowledge‐oriented improvement processes in a business enterprise
Authors: Beckett Ronald C.
Published: June 2004

It is observed that concepts of a learning organization and of knowledge management intended to better utilize the intellectual assets of a business enterprise in supporting continuous improvement and innovation are appealing in principle, but difficult to implement in practice. A significant repertoire of competencies and practices must be acquired or refined, which takes investment and time. A need for performance measurement to demonstrate benefits is also noted. Two case studies illustrate some issues and strategies associated with the implementation of knowledge‐oriented improvement processes. Some “maps” to assist in understanding an enterprise's current position and what may be encountered on the journey ahead are presented.
The implementation process of standardisation
Authors: Gudmundsson Agnar , Boer Harry , Corso Mariano
Published: June 2004

Most companies are experiencing changes in the competitive environment that typesets different sets of requirements in product development management. Action research into the implementation of platform‐based product standardisation shows that there are four key elements that organisations must consider jointly before implementing the concept. These elements are: current and future needs and wants of customers, the organisation's own core competencies, effects on the supply chain of suppliers and distributors, and dominant (i.e. key) technologies built into the products. The paper is intended to raise questions and initiate a discussion about new approaches in product development management, as existing methods are not suitable for current situations.
Role of information systems on the business network formation process: an empirical analysis of the automotive sector
Authors: Lapiedra Rafael , Smithson Steve , Alegre Joaquín , Chiva Ricardo
Published: June 2004

The conditions of change and complexity that characterise the new environment are forcing companies to adopt more flexible organizational structures that allow a quicker adaptation to these continuous changes. States that there are very few companies with enough resources to form their own value chain. Opines this is one of the reasons why the establishment of collaborative agreements among companies seems to be one of the most interesting alternatives in order to complement one another's deficiencies. The formation process of a cooperative business network is analysed, identifying two principal stages: trial and integration. Through an analysis of the network formation process in a case study concerning the Spanish automotive sector, particular issues are identified that characterise the two stages of the process. Shows clearly that the role of information technology and information systems in this situation is very much one of a facilitator.
The characteristics of performance management research
Authors: Thorpe Richard , Beasley Tony
Published: June 2004

Seeks to explore the characteristics of organisational performance management with a view to speculating on the way the development of this emerging academic sub‐discipline might evolve. Identifies just what the nature of a research contribution to the field of performance management might be by briefly reviewing the nature of management as a discipline and how performance management might be located within this context. Performance management is located within two main dimensions: cognitive, and those relating to social organisation as proposed by Becher and Gibbons et al. The methodology compares the field of performance management with analysis that has already been undertaken in an attempt to analyse management as discipline. Analysis shows that research in the performance management field, unlike other more mainstream management research, is likely to be “hard” and “applied” (on the main cognitive dimensions – Becher) and convergent and urban (on the main dimensions in relation to its social organisation – Gibbons). Conclusions are discussed in detail.
Fracture Toughness of Highly Ordered Carbon Nanotube/Alumina Nanocomposites
Authors: Xia Z. , Curtin W. A. , Sheldon B. W.
Published: June 2004

The fracture toughness of highly-ordered multi-wall carbon-nanotube-reinforced alumina composites is calculated from experimental data on nanoindentation cracking. A combined analytical and numerical model, using cohesive zone models for both matrix cracking and nanotube crack bridging and accounting for residual stresses, is developed to interpret the indentation results and evaluate the fracture toughness of the composite. Results show that residual stress and nanotube bridging play important roles in the nanocomposite fracture. The contribution to toughness from the nanotube bridging for cracking transverse to the axis of the nanotubes is calculated to be ∼5 MPa-m1/2. From the nanotube bridging law, the nanotube strength and interfacial frictional stress are also estimated and range from 15–25 GPa and 40–200 MPa, respectively. These preliminary results demonstrate that nanotube-reinforced ceramics can exhibit the interfacial debonding/sliding and nanotube bridging necessary to induce nanoscale toughening, and suggest the feasibility of engineering residual stresses, nanotube structure, and composite geometry to obtain high-toughness nanocomposites.
Static and Dynamic Analysis of Carbon Nanotube-Based Switches
Authors: Dequesnes Marc , Tang Zhi , Aluru N. R.
Published: June 2004

In this paper, we report on molecular dynamics (MD), continuum (based on linear and nonlinear beam theories) and combined molecular dynamics/continuum simulation of carbon nanotube based nanoelectromechanical switches. As a prototype device, we study the pull-in voltage characteristics of a nanoelectromechanical switch made of a suspended single wall nanotube over a ground plane. The various simulations (MD, continuum and combined MD/continuum) have been performed accounting for the electrostatic and van der Waals forces between the nanotube and the ground plane. The results from the nonlinear continuum theory compared well with the results from MD, except, for cases, where nanotube buckling was observed. When buckling occurs, the electromechanical behavior of the switch is simulated by employing a combined MD/continuum approach. The combined MD/continuum approach is computationally more efficient compared to the MD simulation of the entire device. Static and dynamic pull-in, pull-in time and fundamental frequency analysis is presented for fixed-fixed and cantilever carbon nanotube switches.
Deformation Mechanisms of Very Long Single-Wall Carbon Nanotubes Subject to Compressive Loading
Authors: Buehler Markus J. , Kong Yong , Gao Huajian
Published: June 2004

We report atomistic studies of single-wall carbon nanotubes with very large aspect ratios subject to compressive loading. These long tubes display significantly different mechanical behavior than tubes with smaller aspect ratios. We distinguish three different classes of mechanical response to compressive loading. While the deformation mechanism is characterized by buckling of thin shells in nanotubes with small aspect ratios, it is replaced by a rod-like buckling mode above a critical aspect ratio, analogous to the Euler theory in continuum mechanics. For very large aspect ratios, a nanotube is found to behave like a flexible macromolecule which tends to fold due to vdW interactions between different parts of the carbon nanotube. This suggests a shell-rod-wire transition of the mechanical behavior of carbon nanotubes with increasing aspect ratios. While continuum mechanics concepts can be used to describe the first two types of deformation, statistical methods will be necessary to describe the dynamics of wire-like long tubes.
The Effect of Nanotube Waviness and Agglomeration on the Elastic Property of Carbon Nanotube-Reinforced Composites
Authors: Shi Dong-Li , Feng Xi-Qiao , Huang Yonggang Y. , Hwang Keh-Chih , Gao Huajian
Published: June 2004

Owing to their superior mechanical and physical properties, carbon nanotubes seem to hold a great promise as an ideal reinforcing material for composites of high-strength and low-density. In most of the experimental results up to date, however, only modest improvements in the strength and stiffness have been achieved by incorporating carbon nanotubes in polymers. In the present paper, the stiffening effect of carbon nanotubes is quantitatively investigated by micromechanics methods. Especially, the effects of the extensively observed waviness and agglomeration of carbon nanotubes are examined theoretically. The Mori-Tanaka effective-field method is first employed to calculate the effective elastic moduli of composites with aligned or randomly oriented straight nanotubes. Then, a novel micromechanics model is developed to consider the waviness or curviness effect of nanotubes, which are assumed to have a helical shape. Finally, the influence of nanotube agglomeration on the effective stiffness is analyzed. Analytical expressions are derived for the effective elastic stiffness of carbon nanotube-reinforced composites with the effects of waviness and agglomeration. It is found that these two mechanisms may reduce the stiffening effect of nanotubes significantly. The present study not only provides the relationship between the effective properties and the morphology of carbon nanotube-reinforced composites, but also may be useful for improving and tailoring the mechanical properties of nanotube composites.
Tribological Behavior of Aligned Single-Walled Carbon Nanotubes
Authors: Ma Xinling , Wang Hongtao , Yang Wei
Published: June 2004

An abnormal friction law refers to the case where the friction force does not increase monotonically with the normal pressure. We investigate the possibility of abnormal tribological behavior for two surfaces coated with aligned single-walled carbon nanotubes (SWCNTs). Detailed molecular dynamics simulations for aligned SWCNTs predict modulated variation between the kinetic friction force and the applied pressure. The interacting SWCNTs float with respect to each other at about the equilibrium separation of van der Waals interaction, and the wavy contact profile breaks the symmetry of the contacting cross-section. Cases treated by molecular dynamics simulation include two aligned (10,10) SWCNTs with periodic end conditions, and a stack of three aligned (10,10) SWCNTs with free end boundary conditions. A continuum theory based on the wall deflection under finite deformation, in combination with an adhesion criterion similar to the JKR theory, on the other hand, predicts a declining law between the frictional force and the pressure. The correlation of the data obtained through the atomistic and the continuum approaches relies on a deeper understanding on the friction process among SWCNTs.
Mechanics of Axial Compression of Single and Multi-Wall Carbon Nanotubes
Authors: Pantano A. , Boyce M. C. , Parks D. M.
Published: June 2004

A recently developed procedure for modeling the deformation of single and multi-wall carbon nanotubes [13,14] is applied to nanotube buckling and post-buckling under axial compression. Critical features of the model, which is grounded in elastic shell theory, include identification of (a) an appropriate elastic modulus and thickness pair matching both the wall stretching and bending resistances of the single atomic layer nanotube walls, and (b) a sufficiently stiff interwall van der Waals potential to preserve interwall spacing in locally buckled MWNTs, as is experimentally observed. The first issue is illustrated by parametric buckling studies on a SWNT and comparisons to a corresponding MD simulation from the literature; results clearly indicating the inadequacy of arbitrarily assigning the shell thickness to be the equilibrium spacing of graphite planes. Details of the evolution of local buckling patterns in a nine-walled CNT are interpreted based on a complex interplay of local shell buckling and evolving interwall pressure distributions. The transition in local buckling wavelengths observed with increasing post-buckling deformation is driven by the lower energy of a longer-wavelength, multiwall deformation pattern, compared to the shorter initial wavelength set by local buckling in the outermost shell. This transition, however, is contingent on adopting a van der Waals interaction sufficiently stiff to preserve interlayer spacing in the post-buckled configuration.
Application of Multiscale Crystal Plasticity Models to Forming Limit Diagrams
Authors: McGinty Robert D. , McDowell David L.
Published: June 2004

A polycrystal plasticity model is used to conduct parametric studies of forming limit diagrams (FLD) and to compare with experimental data. The Marcinak and Kuczynski [13] method is applied. It is confirmed that the onset of necking is retarded by increases in the ratio of initial band to sheet thickness and material strain rate sensitivity. It was also demonstrated that initial texture plays an important role in FLD response, as has been shown in other recent studies [6,26,7]. It is shown that a texture resulting from plane strain compression to one-tenth of the initial thickness gives a predicted FLD that more closely matches measured data than that based on an initially isotropic texture. The influence of a relatively softer response in terms of effective stress in torsional shear than in compression (i.e., shear softening) on FLDs is investigated with the aid of a hardening surface formulation along with the polycrystal plasticity texture evolution model. It is shown that necking behavior can be significantly affected by shear softening, particularly for initially textured sheets. It is also demonstrated that the hardening surface formulation provides additional flexibility in modeling FLD behavior beyond that afforded by classical polycrystal plasticity.
A Hybrid Approach for Quantifying the Winding Process and Material Effects on Sheet Coil Deformation
Authors: Li Shunping , Cao Jian
Published: June 2004

Excessive coil deformation can complicate normal handling of a wound or rolled coil, cause difficulties in mass production, and introduce undesirable variations in the subsequent manufacturing processes. Four critical factors for coil deformation have been identified, i.e., radial stiffness of the coil material, winding tension, stiffness of the core which supports the coil, and lubrication. In this paper, we advance the understanding of coil deformation by developing an equivalent material model based on the internal stress distribution obtained from a two-dimensional winding-analysis model. The proposed material model is then implemented in a multi-layer finite element model to study the coil deformation under gravitational loading. This proposed framework can quantify the contribution of each factor in the coil deformation and thereby provide more scientific base in the engineering design process. The approach is used to analyze the deformation of laminate sheet coils.
Fundamental Mechanical Properties of Carbon Nanotubes: Current Understanding and the Related Experimental Studies
Authors: Yu Min-Feng
Published: June 2004

Representing a new class of nanoscale material, carbon nanotubes possess many extraordinary mechanical and electronic properties stemming essentially from their unique geometric and chemical structures. Through more than two decades of extensive theoretical and experimental investigations, our understanding on the mechanical properties of carbon nanotubes has greatly improved. The intrinsic mechanical properties of carbon nanotubes, such as their stiffness, strength and deformability, have been relatively well studied and understood; and other mechanics-related properties of carbon nanotubes, such as the defect formation, the fracture mechanism, the interface mechanics and the electromechanics, have also being broadly examined and a comprehensive knowledge of them begins to emerge. I review the current status of research on the mechanical study of carbon nanotubes, especially on the experimental study of their fundamental mechanical properties, such as Young’s modulus, tensile and shear strength, compressibility and deformability. Selected experimental methods and techniques used for the studies will also be introduced. I conclude the review by discussing the new challenges still facing the mechanical study of carbon nanotubes.
Differential effects of TGF-β1 and BMP-4 on the hypoxic induction of cyclooxygenase-2 in human pulmonary artery smooth muscle cells
Authors: Sheares Karen K. K. , Jeffery Trina K. , Long Lu , Yang Xudong , Morrell Nicholas W.
Published: June 2004

Chronic hypoxia-induced pulmonary hypertension results partly from proliferation of smooth muscle cells in small peripheral pulmonary arteries. Previously, we demonstrated that hypoxia modulates the proliferation of human peripheral pulmonary artery smooth muscle cells (PASMCs) by induction of cyclooxygenase-2 (COX-2) and production of antiproliferative prostaglandins ( 55 ). The transforming growth factor (TGF)-β superfamily plays a critical role in the regulation of pulmonary vascular remodeling, although to date an interaction with hypoxia has not been examined. We therefore investigated the pathways involved in the hypoxic induction of COX-2 in peripheral PASMCs and the contribution of TGF-β1 and bone morphogenetic protein (BMP)-4 in this response. In the present study, we demonstrate that hypoxia induces activation of p38MAPK, ERK1/2, and Akt in PASMCs and that these pathways are involved in the hypoxic regulation of COX-2. Whereas inhibition of p38MAPKor ERK1/2 activity suppressed hypoxic induction of COX-2, inhibition of the phosphoinositide 3-kinase pathway enhanced hypoxic induction of COX-2. Furthermore, exogenous TGF-β1 induced COX-2 mRNA and protein expression, and our findings demonstrate that release of TGF-β1 by PASMCs during hypoxia contributes to the hypoxic induction of COX-2 via the p38MAPKpathway. In contrast, BMP-4 inhibited the hypoxic induction of COX-2 by an MAPK-independent pathway. Together, these findings suggest that the TGF-β superfamily is part of an autocrine/paracrine system involved in the regulation of COX-2 expression in the distal pulmonary circulation, and this modulates hypoxia-induced pulmonary vascular cell proliferation.
Histamine selectively interrupts VE-cadherin adhesion independently of capacitive calcium entry
Authors: Winter Michael C. , Shasby Sandra S. , Ries Dana R. , Shasby D. Michael
Published: June 2004

Histamine is an important agent of innate immunity, transiently increasing the flux of immune-competent molecules from the vascular space to the tissues and then allowing rapid restoration of the integrity of the endothelial barrier. In previous work we found that histamine alters the endothelial barrier by disrupting cell-cell adhesion and identified VE-cadherin as an essential participant in this process. The previous work did not determine whether histamine directly interrupted VE-cadherin adhesion, whether the effects of histamine were selective for cadherin adhesion, or whether capacitive calcium flux across the cell membrane was necessary for the effects of histamine on cell-cell adhesion. In the current work we found that histamine directly interrupts adhesion of L cells expressing the type 1 histamine (H1) receptor and VE-cadherin to a VE-cadherin-Fc fusion protein. In contrast, integrin-mediated adhesion to fibronectin of the same L cells expressing the H1 receptor was not affected by histamine, demonstrating that the effects of histamine are selective for cadherin adhesion. Some of the effects of many edemagenic agonists on endothelium are dependent on the capacitive flux of calcium across the endothelial cell membrane. Blocking capacitive calcium flux with LaCl3did not prevent histamine from interrupting VE-cadherin adhesion of transfected L cells, nor did it prevent histamine from interrupting cell-cell adhesion of human umbilical vein endothelial cells. These data support the contentions that histamine directly and selectively interrupts cadherin adhesion and this effect on cadherin adhesion is independent of capacitive calcium flux.
Evidence for a role of heat shock factor 1 in inhibition of NF-κB pathway during heat shock response-mediated lung protection
Authors: Wirth Delphine , Bureau Fabrice , Melotte Dorothée , Christians Elisabeth , Gustin Pascal
Published: June 2004

Heat shock transcription factor (HSF)-1 is recognized as a central component of the heat shock response, which protects against various harmful conditions. However, the mechanisms underlying the protection and the role of HSF-1 in these mechanisms have not yet been clearly elucidated. Using HSF-1 knockout mice ( Hsf1−/−), we examined whether heat shock response-mediated lung protection involved an inhibition of the proinflammatory pathway via an interaction between HSF-1 and NF-κB, in response to cadmium insult. The HSF-1-dependent protective effect against intranasal instillation of cadmium (10 and 100 μg/mouse) was demonstrated by the higher protein content (1.2- and 1.4-fold), macrophage (1.6- and 1.9-fold), and neutrophil (2.6- and 1.8-fold) number in bronchoalveolar fluids, higher lung wet-to-dry weight ratio, and more severe lung damage evaluated by histopathology in Hsf1−/−compared with wild-type animals. These responses were associated with higher granulocyte/macrophage colony-stimulating factor (GM-CSF; 1.7-fold) but not TNF-α concentrations in bronchoalveolar fluids of Hsf1−/−mice compared with those of wild-type animals, indicating that HSF-1 behaved as a repressor of specific cytokine production in our model. To further investigate the mechanism of GM-CSF repression, we analyzed the NF-κB activity and IκB stability. The DNA binding NF-κB activity, in particular p50 homodimer activity, was higher in Hsf1−/−mice than in wild-type mice after cadmium exposure. These results provide a first line of evidence that mechanisms of lung protection depending on HSF-1 involve specific cytokine repression via inhibition of NF-κB activation in vivo.
Pseudomonas aeruginosastimulates phosphorylation of the airway epithelial membrane glycoprotein Muc1 and activates MAP kinase
Authors: Lillehoj Erik P. , Kim Hakryul , Chun Ellen Y. , Kim K. Chul
Published: June 2004

We reported previously that Muc1 on the surface of epithelial cells was a receptor for Pseudomonas aeruginosa (Lillehoj EP, Kim BT, and Kim KC. Am J Physiol Lung Cell Mol Physiol 282: L751–L756, 2002). Other studies showed that the Muc1 cytoplasmic tail (CT) contains multiple phosphorylation sites, some of which are phosphorylated constitutively and associated with signaling proteins. However, the relationship between extracellular P. aeruginosa binding and intracellular signaling is unknown. To investigate the signaling mechanism of Muc1, this study examined phosphorylation of its CT and activation of the extracellular signal-regulated kinase (ERK) in response to stimulation by P. aeruginosa or purified flagellin. Our results showed 1) the Muc1 CT was phosphorylated constitutively on serine and tyrosine, 2) serine phosphorylation was stimulated by bacterial cells or flagellin, and 3) binding of P. aeruginosa or flagellin to Muc1 induced phosphorylation of ERK. These results are the first to demonstrate Muc1 CT phosphorylation and ERK activation in response to a clinically important airway pathogen.