Showing papers by "Worcester Polytechnic Institute published in 2002"

The dynamics of product innovation and firm competences

Abstract: This study examines how product innovation contributes to the renewal of the firm through its dynamic and reciprocal relation with the firm's competences Field research in five high-tech firms of varying age, size, and level of diversification is combined with analysis of existing theory to develop the findings of the study Based on the notion that new products are created by linking competences relating to technologies and customers, a typology is derived that classifies new product projects based on whether a new product can draw on existing competences, or whether it requires competences the firm does not yet have Following organizational learning theory, these options are conceptualized as exploitation and exploration These organizational learning concepts are used to gain a dynamic and path-dependent view of product innovation and firm development, and to reveal the unique nature and challenges of different types of product innovation Copyright © 2002 John Wiley & Sons, Ltd

Indoor geolocation science and technology

Abstract: This article presents an overview of the technical aspects of the existing technologies for wireless indoor location systems. The two major challenges for accurate location finding in indoor areas are the complexity of radio propagation and the ad hoc nature of the deployed infrastructure in these areas. Because of these difficulties a variety of signaling techniques, overall system architectures, and location finding algorithms are emerging for this application. This article provides a fundamental understanding of the issues related to indoor geolocation science that are needed for design and performance evaluation of emerging indoor geolocation systems.

Information quality benchmarks: product and service performance

Abstract: Information quality (IQ) is an inexact science in terms of assessment and benchmarks. Although various aspects of quality and information have been investigated [1, 4, 6, 7, 9, 12], there is still a critical need for a methodology that assesses how well organizations develop information products and deliver information services to consumers. Benchmarks developed from such a methodology can help compare information quality across organizations, and provide a baseline for assessing IQ improvements.

Efficient Adaptive-Support Association Rule Mining for Recommender Systems

Abstract: Collaborative recommender systems allow personalization for e-commerce by exploiting similarities and dissimilarities among customers' preferences We investigate the use of association rule mining as an underlying technology for collaborative recommender systems Association rules have been used with success in other domains However, most currently existing association rule mining algorithms were designed with market basket analysis in mind Such algorithms are inefficient for collaborative recommendation because they mine many rules that are not relevant to a given user Also, it is necessary to specify the minimum support of the mined rules in advance, often leading to either too many or too few ruless this negatively impacts the performance of the overall system We describe a collaborative recommendation technique based on a new algorithm specifically designed to mine association rules for this purpose Our algorithm does not require the minimum support to be specified in advance Rather, a target range is given for the number of rules, and the algorithm adjusts the minimum support for each user in order to obtain a ruleset whose size is in the desired range Rules are mined for a specific target user, reducing the time required for the mining process We employ associations between users as well as associations between items in making recommendations Experimental evaluation of a system based on our algorithm reveals performance that is significantly better than that of traditional correlation-based approaches

A review of non-DLVO interactions in environmental colloidal systems

Abstract: The interaction and behavior of surfaces orcolloids is of quantitative significance inunderstanding the transport and fate ofcompounds and microorganisms in environmentalsystems. Historically, the DLVO model ofcolloid stability has described theseinteractions. This model finds its basis in aforce (energy) balance that comprisesattractive van der Waals and repulsiveelectrostatic interactions. Recently, the DLVOmodel has been found unable to fully describebiotic and abiotic colloidal behavior inaqueous media. The suspending phase (commonlywater) is often treated as a force (energy)transmitting or propagating medium. It isreasonable to believe that the structure ofwater may participate in a more significantfashion. Moreover, other moieties (sorbed anddissolved) may also have non-DLVO effects. Significant work has been focused on extendingthe precepts of the traditional DLVO model toaccommodate these non-DLVO forces (energies). This paper reviews many of the interactionsthat play a role in environmental systems andare not commonly subsumed by the traditionalDLVO model: e.g., hydrogen bonding and thehydrophobic effect, hydration pressure,non-charge transfer Lewis acid baseinteractions, and steric interactions.

Design of large-displacement compliant joints

Abstract: Flexure joints are widely used to approximate the function of traditional mechanical joints, while offering the benefits of high precision, long life, and ease of manufacture. This paper investigates and catalogs the drawbacks of typical flexure connectors and presents several new designs for highly-effective, kinematically-behaved compliant joints. A revolute and a translational compliant joint are proposed (Figure 1), both of which offer great improvements over existing flexures in the qualities of (1) large range of motion, (2) minimal axis drift, (3) increased off-axis stiffness, and (4) reduced stress-concentrations. Analytic stiffness equations are developed for each joint and parametric computer models are used to verify their superior stiffness properties. A catalog of design charts based on the parametric models is also presented, allowing for rapid sizing of the joints for custom performance. Finally, two multi-degree-of-freedom joints are proposed as modifications to the revolute joint. These include a compliant universal joint and a compliant spherical joint, both designed to provide high degrees of compliance in the desired direction of motion and high stiffness in other directions.Copyright © 2002 by ASME

An overview of vibration and seismic applications of NiTi shape memory alloy

Abstract: Shape memory alloys (SMAs) exhibit peculiar thermomechanical, thermoelectrical and thermochemical behaviors under mechanical, thermal, electrical and chemical conditions. Examples of these materials are Cu-based SMAs, NiTi SMAs, ferrous SMAs, shape memory ceramics and shape memory polymers. NiTi SMAs in particular, have unique thermomechanical behaviors such as shape memory effect and pseudoelasticity, which have made them attractive candidates for structural vibration control applications. Numerous studies have been conducted in modeling and applications of NiTi SMAs in structural vibration control. Several active, passive and hybrid energy absorption and vibration isolation devices have been developed utilizing NiTi SMAs. In this paper we present an overview of NiTi behaviors, modeling and applications as well as their limitations for structural vibration control and seismic isolation.

A taxonomy of glyph placement strategies for multidimensional data visualization

Abstract: Glyphs are graphical entities that convey one or more data values via attributes such as shape, size, color, and position. They have been widely used in the visualization of data and information, and are especially well suited for displaying complex, multivariate data sets. The placement or layout of glyphs on a display can communicate significant information regarding the data values themselves as well as relationships between data points, and a wide assortment of placement strategies have been developed to date. Methods range from simply using data dimensions as positional attributes to basing placement on implicit or explicit structure within the data set. This paper presents an overview of multivariate glyphs, a list of issues regarding the layout of glyphs, and a comprehensive taxonomy of placement strategies to assist the visualization designer in selecting the technique most suitable to his or her data and task. Examples, strengths, weaknesses, and design considerations are given for each category of technique. We conclude with some general guidelines for selecting a placement strategy, along with a brief description of some of our future research directions.

Secondary metabolism of hairy root cultures in bioreactors

Abstract: In vitro cultures are being considered as an alternative to agricultural processes for producing valuable secondary metabolites. Most efforts that use differentiated cultures instead of cell suspension cultures have focused on transformed (hairy) roots. Bioreactors used to culture hairy roots can be roughly divided into three types: liquid-phase, gas-phase, or hybrid reactors that are a combination of both. The growth and productivity of hairy root cultures are reviewed with an emphasis on successful bioreactors and important culture considerations. The latter include strain selection, production of product in relation to growth phase, media composition, the gas regime, use of elicitors, the role of light, and apparent product loss. Together with genetic engineering and process optimization, proper reactor design plays a key role in the development of successful large scale production of secondary metabolites from plant cultures.

Dynamics of homogeneous bubbly flows Part 1. Rise velocity and microstructure of the bubbles

Abstract: Direct numerical simulations of the motion of up to 216 three-dimensional buoyant bubbles in periodic domains are presented. The full Navier–Stokes equations are solved by a parallelized finite-difference/front-tracking method that allows a deformable interface between the bubbles and the suspending fluid and the inclusion of surface tension. The governing parameters are selected such that the average rise Reynolds number is about 12–30, depending on the void fraction; deformations of the bubbles are small. Although the motion of the individual bubbles is unsteady, the simulations are carried out for a sufficient time that the average behaviour of the system is well defined. Simulations with different numbers of bubbles are used to explore the dependence of the statistical quantities on the size of the system. Examination of the microstructure of the bubbles reveals that the bubbles are dispersed approximately homogeneously through the flow field and that pairs of bubbles tend to align horizontally. The dependence of the statistical properties of the flow on the void fraction is analysed. The dispersion of the bubbles and the fluctuation characteristics, or ‘pseudo-turbulence’, of the liquid phase are examined in Part 2.

Cooperative advertising, game theory and manufacturer–retailer supply chains

Abstract: Cooperative (co-op) advertising plays a significant role in marketing programs in conventional supply chains and makes up the majority of promotional budgets in many product lines for both manufacturers and retailers. We develop three strategic models for determining equilibrium marketing and investment effort levels for a manufacturer and a retailer in a two-member supply chain. Especially, we address the impact of brand name investments, local advertising, and sharing policy on co-op advertising programs in these models. The first model offers a formal normative approach for analyzing the traditional co-op advertising program where the manufacturer is the leader and the retailer is a follower. The second model provides a further analysis on this manufacturer-dominated relationship. The third model incorporates the recent market trend of retailing power shifts from manufacturers to retailers to analyze efficiencies of co-op advertising programs. We examine the effect of supply chain on the differences in profits resulting from following coordinated strategies as opposed to leader–follower strategies. A cooperative bargaining approach is utilized for determine the best co-op advertising scheme for achieving full coordination in the supply chain.

The Aesthetics of Management Storytelling A Key to Organizational Learning

Abstract: An aesthetics perspective on storytelling contributes to an understanding of how and why some stories are more effective than others. Three ideas about the nature of aesthetic experience—that it is (1) felt meaning from abductive reasoning, (2) characterized by feelings of connectedness, and (3) enjoyed for its own sake-supply criteria for identifying story quality and suggest how to make stories more effective. This idea of good and bad stories informs every aspect of management storytelling, which we illustrate by reviewing the functions of management storytelling using Mintzberg's taxonomy of the roles of the manager Furthermore, through Mintzberg's taxonomy, we show the contributions of aesthetically strong management stories to organizational learning.

A new statistical model for site-specific indoor radio propagation prediction based on geometric optics and geometric probability

Abstract: The ray-tracing (RT) algorithm has been used for accurately predicting the site-specific radio propagation characteristics, in spite of its computational intensity. Statistical models, on the other hand, offers computational simplicity but low accuracy. In this paper, a new model is proposed for predicting the indoor radio propagation to achieve computational simplicity over the RT method and better accuracy than the statistical models. The new model is based on the statistical derivation of the ray-tracing operation, whose results are a number of paths between the transmitter and receiver, each path comprises a number of rays. The pattern and length of the rays in these paths are related to statistical parameters of the site-specific features of indoor environment, such as the floor plan geometry. A key equation is derived to relate the average path power to the site-specific parameters, which are: 1) mean free distance; 2) transmission coefficient; and 3) reflection coefficient. The equation of the average path power is then used to predict the received power in a typical indoor environment. To evaluate the accuracy of the new model in predicting the received power in a typical indoor environment, a comparison with RT results and with measurement data shows an error bound of less than 5 dB.

Overcoming Aesthetic Muteness: Researching Organizational Members’ Aesthetic Experience

Abstract: Direct questioning about the ‘felt sense’ of organizational actions or artefacts is an accepted way to explore organizational members’ aesthetic experience. However, this requires organizational members to be able to talk about their aesthetic experience, to translate that felt sense into language. I suggest this is often difficult due to aesthetic muteness, which is a significant problem, not just for research but for organizational practice in general. I use empirical data to illustrate how this aesthetic muteness is manifested in the research process as organizational members’ difficulty in approaching their experience from an aesthetic perspective, reframing from ‘feeling’ to ‘thinking’, inability to recall aesthetic experience and denial of aesthetic experience. I then speculate that aesthetic muteness might be caused by threats to harmony, efficiency and images of power and effectiveness and that the consequences of aesthetic muteness are aesthetic amnesia, a narrowed conception of organizational ae...

Reproductive Hormone-Induced, STAT3-Mediated Interleukin 6 Action in Normal and Malignant Human Ovarian Surface Epithelial Cells

Abstract: BACKGROUND Reproductive hormones are associated with risk for epithelial ovarian cancer. To determine the effect of such hormones on the activation of interleukin 6 (IL-6)/STAT3 (signal transducer and activator of transcription-3) signaling, which may be involved in ovarian cancer, we investigated the status of STAT3, IL-6, and its receptor in immortalized human ovarian surface epithelial (HOSE) and ovarian cancer (OVCA) cell lines. METHODS Two immortalized HOSE cell lines and two OVCA cell lines were cultured with gonadotropins, sex steroid hormones, and/or IL-6, alone or with specific inhibitors or IL-6-neutralizing antibodies. Expression of IL-6, the IL-6 receptor alpha chain (IL-6Ralpha), and phosphorylated and unphosphorylated STAT3 messenger RNAs (mRNAs) and proteins in all cells was determined. Cell proliferation and soft-agar colony formation were assessed. STAT3 activity was investigated in OVCA cells transfected with a dominant negative STAT3 (Dn-STAT3), wild-type STAT3, or an empty control vector. All statistical tests were two-sided. RESULTS Levels of IL-6 mRNA and protein increased in all cells treated with follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17beta-estradiol, or estrone but increased only in OVCA cells treated with testosterone and 5alpha-dihydrotestosterone. For all lines, IL-6 antibodies partially inhibited hormone-stimulated cell proliferation but completely inhibited IL-6-enhanced cell proliferation. IL-6 induced STAT3 phosphorylation and activation in HOSE cells; STAT3 was constitutively activated in OVCA cells. Higher levels of IL-6Ralpha and STAT3 transcription factors were observed in OVCA cells than in HOSE cells. After transfection, Dn-STAT3 suppressed endogenous STAT3 and inhibited all forms of IL-6-stimulated OVCA cell proliferation (OVCA 429 cells, P<.001; OVCA 432 cells, P<.006), whereas wild-type STAT3 enhanced HOSE cell proliferation (wild-type STAT3 at 0.5 microg/mL in HOSE 306 cells, P<.002; STAT3 at 1.0 microg/mL in HOSE 306 or both concentrations of wild-type STAT3 in HOSE 642 cells, P<.001). CONCLUSIONS The IL-6/STAT3 signaling pathway may mediate FSH-, LH-, and estrogen-stimulated HOSE cell proliferation. Increased IL-6Ralpha expression and constitutive STAT3 activation may be associated with ovarian cancer.

Sustained Potential Oscillations in Proton Exchange Membrane Fuel Cells with PtRu as Anode Catalyst

Abstract: Sustained potential oscillations are experimentally observed in a proton exchange membrane fuel cell with PtRu as anode catalyst and with H 2 /108 ppm CO as the anode feed when operating under a constant current density mode. These oscillations appear at fuel-cell temperatures below 70°C. A threshold value exists for both the current density and the anode flow rate at a given fuel-cell temperature for their onset. The temperature dependence of the oscillation period shows an apparent activation energy around 60 kJ/mol. The potential oscillations are believed to be due to the coupling of anode electro-oxidation of H 2 and CO on the PtRu catalyst surface, on which OH ad is formed more readily, i.e., at lower overpotentials. A simple kinetic model is provided that can reproduce the observed oscillatory phenomenon both qualitatively and quantitatively.

Itoh-Tsujii Inversion in Standard Basis and Its Application in Cryptography and Codes

Abstract: This contribution is concerned with a generalization of Itoh and Tsujii's algorithm for inversion in extension fields GF(q^m). Unlike the original algorithm, the method introduced here uses a standard (or polynomial) basis representation. The inversion method is generalized for standard basis representation and relevant complexity expressions are established, consisting of the number of extension field multiplications and exponentiations. As the main contribution, for three important classes of fields we show that the Frobenius map can be explored to perform the exponentiations required for the inversion algorithm efficiently. As an important consequence, Itoh and Tsujii's inversion method shows almost the same practical complexity for standard basis as for normal basis representation for the field classes considered.

Dynamics of homogeneous bubbly flows Part 2. Velocity fluctuations

Abstract: Direct numerical simulations of the motion of up to 216 three-dimensional buoyant bubbles in periodic domains are presented. The bubbles are nearly spherical and have a rise Reynolds number of about 20. The void fraction ranges from 2% to 24%. Part 1 analysed the rise velocity and the microstructure of the bubbles. This paper examines the fluctuation velocities and the dispersion of the bubbles and the ‘pseudo-turbulence’ of the liquid phase induced by the motion of the bubbles. It is found that the turbulent kinetic energy increases with void fraction and scales with the void fraction multiplied by the square of the average rise velocity of the bubbles. The vertical Reynolds stress is greater than the horizontal Reynolds stress, but the anisotropy decreases when the void fraction increases. The kinetic energy spectrum follows a power law with a slope of approximately 3:6 at high wavenumbers.

Effects of chlorine and ozone on algal cell properties and removal of algae by coagulation

Abstract: The effects of ozone and chlorine on algae were examined with respect to cell surface characteristics, lysis and coagulation ability. Two algae were studied: a green alga ( Scenedesmus quadricauda ) and a diatom ( Cyclotella sp.). Cell properties were characterized using scanning electron micrographs, particle size distributions and electrophoretic mobility measurements. Jar tests were used to evaluate the coagulation of the algal suspensions with a polyaluminium chloride (PACl). The results showed that changes in the characteristics of the algal cells from ozone or chlorine yielded an improvement in removal of Scenedesmus through a combination of lysis and improved coagulation ability with PACl. Cyclotella removal was not enhanced by preoxidation. Additionally, preoxidation increased the organic carbon concentration of the settled water, which could lead to increased tastes and odours and production of disinfection by-products.

Human-Computer Interaction Research in the MIS Discipline

Abstract: Human Computer Interaction (HCI) or Human Factors studies in MIS are concerned with the ways humans interact with information, technologies, and tasks, especially in business, managerial, organizational, and cultural contexts. This article describes the existence and importance of HCI research in the MIS discipline, its historical development, some of its characteristics, publication opportunities, and future research directions. It is believed that HCI is the subject of a strong research stream in MIS, and will continue to be strong in the foreseeable future. It is hoped that HCI studies can provide the evolution of the human centered technology development that enhances our work/job, our various needs, our organizations, our societies, and ourselves.