Showing papers by "Stevens Institute of Technology published in 2001"

One Size Does Not Fit All Projects: Exploring Classical Contingency Domains

Abstract: Not many authors have attempted to classify projects according to any specific scheme, and those who have tried rarely offered extensive empirical evidence. From a theoretical perspective, a traditional distinction between radical and incremental innovation has often been used in the literature of innovation, and has created the basis for many classical contingency studies. Similar concepts, however, did not become standard in the literature of projects, and it seems that theory development in project management is still in its early years. As a result, most project management literature still assumes that all projects are fundamentally similar and that "one size fits all." The purpose of this exploratory research is to show how different types of projects are managed in different ways, and to explore the domain of traditional contingency theory in the more modern world of projects. This two-step research is using a combination of qualitative and quantitative methods and two data sets to suggest a conceptual, two-dimensional construct model for the classification of technical projects and for the investigation of project contingencies. Within this framework, projects are classified into four levels of technological uncertainty, and into three levels of system complexity, according to a hierarchy of systems and subsystems. The study provides two types of implications. For project leadership it shows why and how management should adapt a more project-specific style. For theory development, it offers a collection of insights that seem relevant to the world of projects as temporary organizations, but are, at times, different from classical structural contingency theory paradigms in enduring organizations. While still exploratory in nature, this study attempts to suggest new inroads to the future study of modern project domains.

Providing clarity and a common language to the "fuzzy front end"

Abstract: OVERVIEW:Eight companies that were Process Effectiveness Network members of the Industrial Research Institute attempted to collectively determine the best practices of the Fuzzy Front End (FFE) of innovation. Comparing one company's processes to those of another proved insurmountable because there was neither a common language nor clear and consistent definition of the key elements of the front end. As a result, the group developed a theoretical construct, defined as the New Concept Development (NCD) model, in order to provide a common language and insights on the front end activities. The model consists of three key parts: five front end elements, the engine that powers the elements, and external influencing factors. Proficiency of the FFE was evaluated at 19 companies by using the NCD model. Highly innovative companies were found to be more proficient in the FFE and in several elements of the NCD model.

Analysis of LSB based image steganography techniques

Abstract: There have been many techniques for hiding messages in images in such a manner that the alterations made to the image are perceptually indiscernible. However, the question whether they result in images that are statistically indistinguishable from untampered images has not been adequately explored. We look at some specific image based steganography techniques and show that an observer can indeed distinguish between images carrying a hidden message and images which do not carry a message. We derive a closed form expression of the probability of detection and false alarm in terms of the number of bits that are hidden. This leads us to the notion of steganographic capacity, that is, how many bits can we hide in a message without causing statistically significant modifications? Our results are able to provide an upper bound on the this capacity. Our ongoing work relates to adaptive steganographic techniques that take explicit steps to foil the detection mechanisms. In this case we hope to show that the number of bits that can be embedded increases significantly.

Nonlinear acoustic interaction on contact interfaces and its use for nondestructive testing

Abstract: Recent theoretical and experimental studies demonstrated that a weakly or incompletely bonded interfaces exhibit highly nonlinear behavior. One of acoustic manifestations of such nonlinearity is the modulation of a probing high-frequency ultrasonic wave by low-frequency vibration. The vibration varies the contact area modulating the phase and amplitude of higher frequency probing wave passing through the interface. In the frequency domain, the result of this modulation manifests itself as side-band spectral components with respect to the frequency of the probing wave. This modulation effect has been observed experimentally for various materials (metals, composites, concrete, sandstone, glass) with various types of contact-type defects (interfaces): cracks, debondings, delaminations, and microstructural material damages. Study of this phenomenon revealed correlation between the developed modulation criterion and the quantitative characteristics of the interfaces, such as its size, loading condition, and bonding strength. These findings have been used for the development of an innovative nondestructive evaluation technique, namely Vibro-Acoustic Modulation Technique. Two modifications of this technique have been developed: Vibro-Modulation (VM) and Impact-Modulation (IM), employing CW and impact-induced vibrations, respectively. The examples of applications of these methods include crack detection in steel pipes, aircraft and auto parts, bonded composite plates etc. These methods also proved their effectiveness in the detection of cracks in concrete.

Social Interaction: A Determinant of Entrepreneurial Team Venture Success

Abstract: An important issue to explain the success of new ventures is mostly ignored by the research of entrepreneurship: the social interaction within entrepreneurial teams. The purpose of this paper is to introduce the concept of social interaction, which was originally developed for innovation teams in the field of entrepreneurship research and theory. The theoretical discussion proves if an adoption of the social interaction to the field of entrepreneurship is theoretically possible. Using the data of 159 German entrepreneurial teams, the effects of social interaction on new business success are empirically proven. The introduced measurement model, which consists of six dimensions, shows a high quality in the empirical test. The quality of the social interaction within entrepreneurial teams is crucial for the new venture success. An empirical comparison with the frequently used team conflicts confirm that the measurement of conflicts is not a sufficient substitute measurement for social interaction. Overall, the social interaction in entrepreneurial teams could be seen as an important but not only factor of business success.

Micro-damage diagnostics using Nonlinear Elastic Wave Spectroscopy (NEWS)

Abstract: Nonlinear elastic wave spectroscopy (NEWS) represents a class of powerful tools which explore the dynamic nonlinear stress–strain features in the compliant bond system of a micro-inhomogeneous material and link them to micro-scale damage. Hysteresis and nonlinearity in the constitutive relation (at the micro-strain level) result in acoustic and ultrasonic wave distortion, which gives rise to changes in the resonance frequencies as a function of drive amplitude, generation of accompanying harmonics, nonlinear attenuation, and multiplication of waves of different frequencies. The sensitivity of nonlinear methods to the detection of damage features (cracks, flaws, etc.) is far greater than can be obtained with linear acoustical methods (measures of wavespeed and wave dissipation). We illustrate two recently developed NEWS methods, and compare the results for both techniques on roofing tiles used in building construction.

Monolithically integrated, flexible display of polymer-dispersed liquid crystal driven by rubber-stamped organic thin-film transistors

Abstract: This letter describes the monolithic integration of rubber-stamped thin-film organic transistors with polymer-dispersed liquid crystals (PDLCs) to create a multipixel, flexible display with plastic substrates. We report the electro-optic switching behavior of the PDLCs as driven by the organic transistors, and we show that our displays operate robustly under flexing and have a contrast comparable to that of newsprint.

Workflow Automation: Overview and Research Issues

Abstract: Workflow management systems, a relatively recent technology, are designed to make work more efficient, integrate heterogeneous application systems, and support interorganizational processes in electronic commerce applications. In this paper, we introduce the field of workflow automation, the subject of this special issue of Information Systems Frontiers. In the first part of the paper, we provide basic definitions and frameworks to aid understanding of workflow management technologies. In the remainder of the paper, we discuss technical and management research opportunities in this field and discuss the other contributions to the special issue.

Blind adaptive algorithms for minimum variance CDMA receivers

Abstract: Constrained optimization methods have received considerable attention as a means to derive blind multiuser receivers with low complexity. The receiver's output variance is minimized subject to appropriate constraints which depend on the multipath structure of the signal of interest. When multipath is present, the constraint equations can be written in parametric form, and the constraint parameters jointly optimized with the linear receiver's parameters. We develop adaptive solutions for this joint, constrained optimization problem. Both stochastic gradient and recursive least-square-type algorithms are developed. The performance of the proposed methods is compared with other blind and trained methods and turns out to be close to the trained minimum mean-square-error receiver.

Redox transformations of arsenic and iron in water treatment sludge during aging and TCLP extraction.

Abstract: Laboratory experiments and modeling studies were performed to investigate the redox transformations of arsenic and iron in water treatment sludge during aging, and to evaluate the impact of those transformations on the leachability of arsenic determined with the U.S. EPA toxicity characteristic leaching procedure (TCLP). When the backwash suspension samples collected from a California surface water treatment plant were aged in closed containers for a few weeks, soluble arsenic increased from less than 5 microg/L to as high as 700 microg/L and then decreased dramatically because of biotic reduction of arsenate [As(V)], ferric oxyhydroxide, and sulfate. The experimental results and the thermodynamic models showed that arsenic mobility can be divided into three redox zones: (a) an adsorption zone at pe > 0, which is characterized by strong adsorption of As(V) on ferric oxyhydroxide; (b) a mobilization (transition) zone at -4.0 < pe < 0, where arsenic is released because of reduction of ferric oxyhydroxide to ferrous iron and As(V) to arsenite [As(III)]; and (c) a reductive fixation zone at pe < -4.0, where arsenic is immobilized by pyrite and other reduced solid phases. The TCLP substantially underestimated the leachability of arsenic in the anoxic sludge collected from sludge ponds because of the oxidation of Fe(II) and As(III) by oxygen. The leaching test should be performed in zero-headspace vessels or under nitrogen to minimize the transformations of the redox-sensitive chemical species.

Intrinsic viscosity and the electrical polarizability of arbitrarily shaped objects

Abstract: The problem of calculating the electric polarizability tensor ${\ensuremath{\alpha}}_{e}$ of objects of arbitrary shape has been reformulated in terms of path integration and implemented computationally. The method simultaneously yields the electrostatic capacity C and the equilibrium charge density. These functionals of particle shape are important in many materials science applications, including the conductivity and viscosity of filled materials and suspensions. The method has been validated through comparison with exact results (for the sphere, the circular disk, touching spheres, and tori), it has been found that ${10}^{6}$ trajectories yield an accuracy of about four and three significant figures for C and ${\mathbf{\ensuremath{\alpha}}}_{\mathbf{e}},$ respectively. The method is fast: For simple objects, ${10}^{6}$ trajectories require about 1 min on a PC. It is also versatile: Switching from one object to another is easy. Predictions have also been made for regular polygons, polyhedra, and right circular cylinders, since these shapes are important in applications and since numerical calculations of high stated accuracy are available. Finally, the path-integration method has been applied to estimate transport properties of both linear flexible polymers (random walk chains of spheres) and lattice model dendrimer molecules. This requires probing of an ensemble of objects. For linear chains, the distribution function of C and of the trace $({\mathbf{\ensuremath{\alpha}}}_{\mathbf{e}}),$ are found to be universal in a size coordinate reduced by the chain radius of gyration. For dendrimers, these distribution functions become increasingly sharp with generation number. It has been found that C and ${\ensuremath{\alpha}}_{e}$ provide important information about the distribution of molecular size and shape and that they are important for estimating the Stokes friction and intrinsic viscosity of macromolecules.

Acoustic emission detection using fiber Bragg gratings

Abstract: A systematic study of acoustic emission detection using fiber Bragg grating sensors has been carried out over the last year. In this, we attempt to use the fiber Bragg grating to sense the dynamic strain created by a passing ultrasonic wave signal. Our goal here is to see if such a sensor is possible, and if so, what the detection sensitivity and limitations will be. To answer these questions, we carried out several experiments involving the detection of simulated acoustic emission events. In the first experiment, we attach fiber Bragg grating to the surface of a piezoceramic resonator which is driven by a signal generator. We were able to detect the resulting surface vibration of the resonator up to 2.1 MHz. In the second experiment, we attach a fiber Bragg grating to the surface of an aluminum plate. We excite an acoustic wave using an ultrasonic transducer located at various positions of the aluminum plate. In this way, we demonstrated that the fiber Bragg Grating sensor is capable of picking up the signal coming from a distance (up to 30 cm) for up to 2.5 MHz. In a third experiment, we use the same fiber Bragg grating on aluminum plate set up, but set up an acoustic signal by either a gentle knock on the plate by a pin, or by breaking a pencil lead on the plate. We were able to detection acoustic emission set up by pencil lead breaking up to a frequency of 30 kHz. Higher frequency components were not detected mainly due to the limitation of available electronic equipment at this time (higher frequency band-pass filters and amplifiers. In all the above-mentioned experiments we use a match Bragg grating to demodulate the detected optical signal and use a dual channel scheme for electronic data acquisition and processing (a signal channel and a reference channel).

Viscosimetric, Hydrodynamic, and Conformational Properties of Dendrimers and Dendrons

Abstract: Controlling the molecular architecture of dendrimers is crucial for their intended use in applications such as drug delivery, biocides, gene transfer, catalyst supports, and processing aids (see refs 1-3). The molecular conformation in solution and the melt, which will control efficacy in such applications, has been the subject of theory,4,5 molecular,6 and coarse-grained simulations7-11 and extensive experimentation by X-ray, light and neutron scattering,12-21 and rheology.12,13,22-27 Of fundamental interest is the location of the terminal groups and molecular density profile as a function of the generation number. Direct, quantitative comparison of theory, experiment, and simulation is often complicated by the various levels of approximation used in the modeling and the need to accurately specify the physical properties of chemical groups and their interactions with the solvent. However, one useful, quantitative indicator of molecular conformation is the ratio of the radius of gyration (Rg) to the viscosimetric radius (Rη) or the hydrodynamic radius (Rh). These ratios can be computed from the molecular architecture without specifying the chemical details and depend primarily on the mass distribution. As such, they are an indication of overall macromolecular geometry and hydrodynamic draining. The radius of gyration is typically calculated from static scattering measurements, while the hydrodynamic radius (or equivalent sphere radius) is determined by dynamic light scattering or other diffusion measurements. For reference, a solid sphere yields a value of Rg/Rh ) Rg/Rη ) x(3/5) ≈ 0.77. Core weighting of the density distribution decreases these ratios, and values much higher (∼1.22 ln(L/D), with L/D the aspect ratio) can be achieved by a slender-rod geometry. Larger ratios are generally observed for polymers in solution; the experimental results of Schmidt and Burchard28 for linear polystyrene and poly(methyl methacrylate) in Θ solvents yield ratios of Rg/Rh ) 1.27 and 1.16, respectively. The viscosimetric radius is also an effective hydrodynamic sphere radius but is determined from intrinsic viscosity measurements. Although equal for hard spheres, Rη is generally different from Rh due to the different flow fields generated during the two measurements. The ratio Rg/Rη is inversely related to the Flory-Fox parameter and can be thought of as a measure of how well the molecule is drained by the solvent. Molecules that are easily drained have small viscosimetric radii and Flory-Fox parameters; thus, Rg/Rη becomes large. Using relationships in Flory,29 the ratio Rg/Rη is calculated as 1.17 for a Gaussian coil in a Θ solvent, based on experimental data for several linear polymers. For highly branched molecules the density of segments is higher than for linear polymers.30 This results in a larger Flory-Fox parameter (larger Rη) and a smaller value of Rg/Rη. It is expected that these results also depend on the solvent quality; collapsing the polymer in poor solvents should reduce the value toward that of a solid sphere, while expansion of the polymer in good solvents is expected to increase the ratio. It is clear that these simple comparisons of measurable molecular dimensions can provide valuable information about the conformation of polymers in solution. Here, we extend this idea to explore the effects of extreme branching on polymer conformation, where monodisperse dendrimers of varying generation provide clean model systems for investigation. To begin, we analyze the available experimental and theoretical data in the literature. The two most heavily studied systems are poly(propyleneimine) (PPI) and poly(amidoamine) (PAMAM) dendrimers. We then present new smallangle neutron scattering data for several generations of poly(benzyl ether) monodendrons in a good solvent. Comparing this information with previously published intrinsic viscosity results sheds light on the effect of dendritic architecture, solvent quality, and steric crowding on molecular conformation. The new results and the literature results are compared with recent theoretical calculations and simulations of these geometric properties to assess their validity.

Effects of Pt incorporation on the isothermal oxidation behavior of chemical vapor deposition aluminide coatings

Abstract: The effects of Pt incorporation on the isothermal oxidation and diffusion behavior of low-sulfur aluminide bond coatings were investigated. Aluminide (NiAl) coatings and Pt-modified aluminide (Ni,Pt)Al coatings were synthesized on a low-sulfur, yttrium-free single-crystal Ni-based superalloy by a high-purity, low-activity chemical vapor deposition (CVD) aluminizing procedure. The isothermal oxidation kinetics and scale adhesion behavior of CVD NiAl and (Ni,Pt)Al coatings before and after isothermal oxidation were determined by electron microprobe analysis. Platinum did not reduce oxide-scale growth kinetics. No significant differences in bulk refractory metal (W, Ta, Re, and Mo) distributions were observed as a result of Pt incorporation. Spallation of the alumina scale and the formation of large voids along the oxide-metal interface were commonly observed over the NiAl coating grain boundaries after 100 hours at 1150 °C. In contrast, no spallation of Al2O3 scales occurred on (Ni,Pt)Al coating surfaces or grain boundaries, although the sulfur content in the CVD (Ni,Pt)Al coatings was higher than that of the CVD NiAl coatings. Most significantly, no voids were observed at the oxide-metal interface on (Ni,Pt)Al coating surfaces or cross sections after 200 hours at 1150 °C. It was concluded that a major beneficial effect of Pt incorporation on an aluminide coatings oxidation resistance is the elimination of void growth at the oxide-metal interface, likely by mitigation of detrimental sulfur effects.

Experimental and analytical studies on a high-resolution OFDM carrier frequency offset estimator

Abstract: In orthogonal frequency-division multiplexing (OFDM) communications, carrier frequency offset must be estimated and compensated at the receiver to maintain orthogonality. In this paper, we examine the performance of a blind carrier frequency offset estimation algorithm for OFDM communications, Experiments were conducted on a system operating at close to 2 Mbits/s. Insights obtained from these experiments provided the motivation to explore the fundamental relationships between estimator performance and multiple system parameters such as the signal-to-noise ratio, number of data samples, frequency-selective fading, and power loading. We examine the sensitivity of the blind carrier frequency offset estimation algorithm using first-order perturbation analysis. In particular, we derive a closed-form expression for the mean square error of the carrier frequency offset estimator and present tradeoff studies for the high-resolution blind estimator performance. The analytical and simulation studies are in good agreement with experimental results.

Understanding the color of human skin

Abstract: The automated detection of humans in computer vision as well as the realistic rendering of people in computer graphics necessitates a better understanding of human skin reflectance Prior vision and graphics research on this topic has primarily focused on images acquired with conventional color cameras. Although tri-color skin data is prevalent, it does not provide adequate information for explaining skin color or for discriminating between human skin and dyes designed to mimic human skin color. A better understanding of skin reflectance can be achieved through spectrographic analysis. Previous work in this field has largely been undertaken in the medical domain and focuses on the detection of pathology. Our work concentrates on the impact of skin reflectance on the image formation process. In our radiometric facility we measure the light reflected from the skin using a high resolution, high accuracy spectrograph under precisely calibrated illumination conditions. This paper presents observations from the first body of data gathered at this facility. From the measurements collected thus far, we have observed population-independent factors of skin reflectance. We show how these factors can be exploited in skin recognition. Finally, we provide a biological explanation for the existence of a distinguishing pattern in human skin reflectance.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Multispectral skin color modeling

Abstract: The automated detection of humans in computer vision as well as the realistic rendering of people in computer graphics necessitates improved modeling of the human skin color. We describe the acquisition and modeling of skin reflectance data densely sampled over the entire visible spectrum. The data collected through a spectrograph allows us to explain skin color (and its variations) and to discriminate between human skin and dyes designed to mimic human skin. We study the approximation of these data using several sets of basis functions. Our study shows that skin reflectance data can best be approximated by a linear combination of Gaussians or their first derivatives. This result has a significant practical impact on optical acquisition devices: the entire visible spectrum of skin reflectance can now be captured with a few filters of optimally chosen central wavelengths and bandwidth.

Type-based hot swapping of running modules

Abstract: While dynamic linking has become an integral part of the run-time execution of modern programming languages, there is increasing recognition of the need for support for hot swapping of running modules, particularly in long-lived server applications. The interesting challenge for such a facility is to allow the new module to change the types exported by the original module, while preserving type safety. This paper describes a type-based approach to hot swapping running modules. The approach is based on a reflective mechanism for dynamically adding type sharing constraints to the type system, realized by programmer-defined version adapters in the run-time.

Sliding and abrasive wear resistance of thermal-sprayed WC-CO coatings

Abstract: We studied the resistance of the coatings to abrasive and unlubricated sliding wear of 40 WC/Co coatings applied by high velocity oxygen fuel (HVOF), high-energy plasma spray (HEPS), and high velocity plasma spray (HVPS), using commercial and nanostructured experimental powders. The hardness of the coatings varies from 3 to 13 GPA, which is much lower than that of sintered samples (10 to 23 GPA) because of the porosity of the coatings. Phase analysis by x-ray diffraction revealed various amounts of decarburization in the coatings, some of which contain WC, W2C, W, and η phase. The abrasive and sliding wear resistance is limited by the hardness of the samples. For a given hardness, the wear resistance is lowered by decarburization, which produces a hard but brittle phase. Nanocarb powders have the shape of thin-walled hollow spheres that heat up rapidly in the gun and are more prone to decarburization than commercial materials. The work shows that, in order to obtain the performance of nanostructured coatings, the powder and spray techniques must be modified.

Snow grain size retrieved from near-infrared radiances at multiple wavelengths

Abstract: A comprehensive forward radiative transfer model is used to construct a snow grain size retrieval algorithm that relies on the use of NIR radiances. Data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) at the wavelengths 0.86, 1.05, 1.24 and 1.73 µm are used to retrieve snow grain size. Based on a single-layer (homogeneous) snow model, the retrieved snow grain size appears to depend on wavelength. The photon penetration depth defined as the e-folding flux attenuation depth has be computed for different snow grain sizes and different wavelengths. It reveals that this apparent wavelength dependence occurs because (i) the snow grain size generally increases with depth, and (ii) the photon penetration depth decreases with increasing wavelength. The results show that the wavelength dependence of the photon penetration depth can be used to retrieve the depth dependence of the snow grain size.

High-speed modulation and free-space optical audio/video transmission using quantum cascade lasers

Abstract: The high-speed direct modulation response of mid-infrared quantum cascade (QC) lasers is investigated up to a frequency of 2 GHz, showing high-frequency data transmission capabilities. The application of QC lasers to optical wireless communications is discussed and demonstrated in a free-space television link over a distance of 70 m.

Technology Stage Gate: A Structured Process for Managing High Risk, New Technology Projects

Abstract: Traditional Stage GateTM (SG) (Cooper, 1993) or PACE® processes (McGrath and Akiyama, 1996) assume that there is little uncertainty associated with the technologies to be utilized. The inability to manage high-risk technologies, as part of product development, is frequently the cause of canceled or significantly delayed new product development projects. Unlike product development, the ultimate outcomes of technology development efforts are unpredictable. Prematurely introducing a technology into the product development process, when there is high uncertainty that the technology will ever meet the desired specifications, often leads to project delays, project uncertainty and project cancellation.

High-speed digital data transmission using mid-infrared quantum cascade lasers

Abstract: High-speed mid-infrared quantum cascade lasers with direct modulation bandwidth of approximately 7 GHz have been developed. Error-free digital data transmission at 2.5 Gbit/s is demonstrated with devices emitting at 8 µm and operating at temperatures up to 85 K.

Validity of the diffusion approximation in bio-optical imaging

Abstract: Accurate numerical simulations based on rigorous radiative transfer theory are used to assess the validity of the diffusion approximation that is frequently used in bio-optical imaging. These simulations show that the error is large for a non-index-matched boundary between air and tissue. This weakness of the diffusion approximation underscores the need to understand how diffusion theory can be used to extract accurate values of tissue optical properties. A validity criterion for the diffusion approximation is established on the basis of the single-scattering albedo a and the asymmetry factor g for a slab with index-matched boundaries.