Showing papers by "Stevens Institute of Technology published in 1997"

Project success: a multidimensional, strategic concept

Abstract: Summary form only given. What does project success mean? When a project is completed on time and within the original budget, is it a success? Or even when it fails to meet these objectives but succeeds in meeting its specified requirements, is it then a successfully completed project? The objective of this work is to develop a universal framework for the assessment of project success to help organizations cope with the above questions. We view project success as a strategic multidimensional concept where project efforts must be aligned with the strategic long-term goals of the organization. We employ in this study a combination of qualitative and quantitative methods, and two data sets which included more than 140 projects. Using a project specific approach, our analysis resulted in four distinct success dimensions: (1) project efficiency, (2) impact on the customer, (3) direct business and organizational success, and (4) preparing for the future. These dimensions represent different points of view, different concerns of the organization, and different time horizons. We demonstrate how the relative importance of these dimensions varies with the time passed since project completion, as well as with the project type. Finally, we provide a set of guidelines for project managers and policy makers at the top level.

The relative importance of project success dimensions

Abstract: Traditionally, the success of a project is assessed using internal measures such as technical and operational goals, and meeting schedule and budget. More recently, it has been recognized that several other measures should be used to define project success. These measures reflect external effectiveness: the project's impact on its customers, and on the developing organization itself. In our study of 110 defense projects performed by Israeli industry, we used a multidimensional approach to measure the success of defense projects. Based on previous studies, we defined four dimensions of success: meeting design goals; benefits to the customer; benefits to the developing organization; and benefits to the defense and national infrastructure. For each project, we asked three different stakeholders (the customer, the developing organization, and the coordinating office within the Ministry of Defense) for their views on the relative importance of these dimensions of success. Analysis of the data revealed that the dimension benefits to the customer is by far the most important success dimension. The second in importance is meeting design goals. The other two dimensions are relatively unimportant.

Inverse filtering criteria for CDMA systems

Abstract: Linear blind CDMA receivers are derived using inverse filtering criteria. The receiver parameters are directly obtained without explicit estimation of the system/channel. Both synchronous and asynchronous cases are addressed, and multipath distortions are explicitly considered and compensated for. The approach is based on minimizing the receiver's output energy subject to appropriate constraints. Similar approaches have been used before in multiuser systems but without considering multipath distortions. Batch and adaptive blind algorithms are derived that are near-far resistant and do not require knowledge of the interfering users' codes. Global convergence is shown, optimality and performance issues are discussed, and some illustrative simulations are presented.

The Effects of Peer Feedback on Team Member Behavior

Abstract: We examined the effects of peer feedback on subsequent behavior using a four-dimensional model of team behavior. Participants (N= 75) were randomly assigned to teams, and teams were randomly assigned to one of three experimental conditions: feedback, exposure, or control. In the feedback condition, participants rated themselves and each other using a 24-item behavioral observation scale after completing the first of two decison-making tasks. Before performing the second task, they received individualized feedback reports summarizing their self- and peer ratings. Those assigned to the exposure condition completed the behavioral observation scale after the first task but did not receive feedback. The second task was videotaped and rated by experts blind to experimental condition. Results showed significantly higher ratings for participants in the feedback and exposure conditions. The findings extend previous research on multisource feed-back by isolating exposure to key behaviors as an important variable in...

Blind estimation of direct sequence spread spectrum signals in multipath

Abstract: Self-recovering receivers for direct-sequence spread-spectrum signals with unknown spreading codes are discussed in this paper. Applications include signal interception, jamming, and low probability of intercept (LPI) communications. A multirate/multichannel, discrete-time model of the spread spectrum signal is introduced, which establishes links with array processing techniques. Borrowing blind channel estimation ideas, which were originally developed in the context of fractionally spaced equalizers or receivers with multiple antennas, linear solutions are obtained that are independent of the input distribution. The signal interception problem is further studied, and a zero-forcing (ZF) receiver/equalizer is proposed to recover the transmitted data. Its performance is analyzed, and some illustrative simulations are presented.

Transmitter induced cyclostationarity for blind channel equalization

Abstract: Fractional sampling has received considerable interest recently as a means of developing blind equalization techniques without resorting to higher order statistics. Instead, cyclostationarity introduced at the receiver by fractional sampling is exploited. We show that simpler solutions are possible if cyclostationarity is introduced at the transmitter instead of the receiver. We propose specific coding and interleaving strategies at the transmitter that induce cyclostationarity and facilitate the equalization task. Novel batch and adaptive equalization algorithms are derived that make no assumptions on the channel zeros locations. Subspace methods are also proposed and, in the absence of noise, guarantee perfect estimation from finite data. Synchronization issues and bandwidth considerations are briefly discussed, and simulation examples are presented.

Software Reuse: Survey and Research Directions

Abstract: Software reuse is the use of software resources from all stages of the software developmentprocess in new applications. Given the high cost and difficulty of developing high quality software, theidea of capitalizing on previous software investments is appealing. However, software reuse has not beenas effective as expected and has not been very broadly or systematically used in industry. This papersurveys recent software reuse research using a framework that helps identify and organize the manyfactors that must be considered to achieve the benefits of software reuse in practice. We argue thatsoftware reuse needs to be viewed in the context of a total systems approach that addresses a broad rangeof technical, economic, managerial, organizational and legal issues and conclude with a summary of themajor research issues in each of these areas.

Viscoelastic material functions of noncolloidal suspensions with spherical particles

Abstract: We have characterized various steady and time-dependent material functions of suspensions of a non-Newtonian binder, poly(dimethyl siloxane), incorporated with 10%–60% by volume of hollow and spherical glass beads The material functions included storage and the loss moduli, shear stress and first normal stress difference growth and relaxation, relaxation modulus upon step strain and creep and recovery behavior Both constant shear stress and shear rate experiments were carried out using multiple rheometers over a broad temperature range (−35 to 40 °C) while following sample fracture and wall slip effects With increasing volume fraction, φ, of the noncolloidal particles, the strain range, over which linear viscoelastic behavior is observed, became narrower and the relaxation time of the suspension increased Increasing solid content gave rise to the development of the yield stress and the dependence of large amplitude oscillatory shear properties on time and deformation history The yield stress values i

Programmable lock and security system therefor

Abstract: Locks (2) for the transportation industry are programmable with a keypad and with handheld activators (116, 118), the activators being programmable by a central system (134) and activators via IR transmitters and receivers. Operator PIN numbers and access codes manifesting the supervisory level of authority are encoded in each lock (2) which are programmed to open a given number of times in a given time period with or without entry of a code and include a lockout feature for disabling the lock in case of invalid code entry. Each lock has a lock history containing the number of incomplete opening transactions, when they occured and the operator codes associated therewith. The locks are opened by IR transmission of the appropriate codes or by keypad entries. One or more individuals at different levels of authority may open one or more locks in a given time frame a given number of times. Each lock records its transaction history which is displayed and downloaded for system evaluation.

Ab initio relativistic effective potentials with spin-orbit operators. VII. Am through element 118

Abstract: Ab initio averaged relativistic effective core potentials (AREP) and spin-orbit (SO) operators are reported for the elements Am through element 118. Two sets have been calculated for certain elements to provide AREPs with varying core/valence space definition, thereby permitting the treatment of core/valence correlation interactions. The AREPs and SO operators are tabulated as expansions in Gaussian-type functions (GTF). GTF valence basis sets are derived for the lowest energy state of each atom. The reliability of the AREPs and SO operators is gauged by comparing calculated atomic orbital eigenvalues and SO splitting energies with all-electron relativistic values.

Percolation in magnetic composites

Abstract: Electric and magnetic properties of composite materials consisting of low density polyethylene filled with powdered ferromagnetic materials were investigated. The volume fractions of the fillers were varied from 10% up to the theoretical maximum packing fractions, i.e. between 0.70 and 0.77, so that the percolation phenomenon could be investigated. The ferromagnetic fillers used were HyMu 800 (a nickel-iron-molybdenum alloy), MnZn ferrite and NiZn ferrite. The particle sizes and size distributions of the fillers were well characterized by image analysis techniques. Based on the particle size distribution the maximum loading levels of fillers as permitted by geometric considerations were calculated. The properties of the composites characterized included: volume and surface resistivities, dielectric constants, electrical loss factors and magnetic permeabilities.

The new taxonomy of systems: toward an adaptive systems engineering framework

Abstract: Systems engineering is developing rapidly, while new standards are created and new tools are being developed. However, the theoretical understanding and the conceptual foundation of systems engineering are still in their early stages. For example, although real-world systems exhibit considerable differences, there is very little distinction in the literature between the system type and the description of its actual system engineering pursuit. We suggest here a new approach to systems engineering. It is based on the premise that the actual process of systems engineering must be adaptive to the real system type. Using this concept, we present a two-dimensional (2-D) taxonomy in which systems are classified according to four levels of technological uncertainty, and three levels of system scope. We then describe the differences found in systems engineering styles in various areas, such as system requirements, functional allocation, systems design, project organization, and management style. We also claim that adapting the wrong system and management style may cause major difficulties during the process of system creation. Two examples will be analyzed to illustrate this point: the famous Space Shuttle case and one of the system development projects we studied.

Subspace methods for blind estimation of time-varying FIR channels

Abstract: Novel linear algorithms are proposed in this paper for estimating time-varying FIR systems, without resorting to higher order statistics. The proposed methods are applicable to systems where each time-varying tap coefficient can be described (with respect to time) as a linear combination of a finite number of basis functions. Examples of such channels include almost periodically varying ones (Fourier series description) or channels locally modeled by a truncated Taylor series or by a wavelet expansion. It is shown that the estimation of the expansion parameters is equivalent to estimating the second-order parameters of an unobservable FIR single-input-many-output (SIMO) process, which are directly computed (under some assumptions) from the observation data. By exploiting this equivalence, a number of different blind subspace methods are applicable, which have been originally developed in the context of time-invariant SIMO systems. Identifiability issues are investigated, and some illustrative simulations are presented.

A new synthesis approach for feedback neural networks based on the perceptron training algorithm

Abstract: In this paper, a new synthesis approach is developed for associative memories based on the perceptron training algorithm The design (synthesis) problem of feedback neural networks for associative memories is formulated as a set of linear inequalities such that the use of perceptron training is evident The perceptron training in the synthesis algorithms is guaranteed to converge for the design of neural networks without any constraints on the connection matrix For neural networks with constraints on the diagonal elements of the connection matrix, results concerning the properties of such networks and concerning the existence of such a network design are established For neural networks with sparsity and/or symmetry constraints on the connection matrix, design algorithms are presented Applications of the present synthesis approach to the design of associative memories realized by means of other feedback neural network models are studied To demonstrate the applicability of the present results and to compare the present synthesis approach with existing design methods, specific examples are considered

Glow plasma discharge device having electrode covered with perforated dielectric

Abstract: A method and apparatus for stabilizing glow plasma discharges by suppressing the transition from glow-to-arc includes a perforated dielectric plate having an upper surface and a lower surface and a plurality of holes extending therethrough. The perforated dielectric plate is positioned over the cathode. Each of the holes acts as a separate active current limiting micro-channel that prevents the overall current density from increasing above the threshold for the glow-to-arc transition. This allows for a stable glow discharge to be maintained for a wide range of operating pressures (up to atmospheric pressures) and in a wide range of electric fields include DC and RF fields of varying strength.

Design of wavelength-routed optical networks for packet switched traffic

Abstract: We consider the problem of designing a logical optical network topology for a given physical topology (or fiber layout) and a given traffic demand matrix between the end-users. Traffic between the end-users is carried in a packet-switched form and the objective of our logical topology design is to minimize the maximum congestion on the logical connections in the logical topology. The logical connections are realized by wavelength continuous paths or lightpaths between end-users and they are routed via wavelength-selective routers. Note that a topology with lower maximum link congestion will allow its traffic demand matrix to be scaled up by a larger factor. In the logical topology each node is equipped with a limited number of optical transceivers, hence logical connections cannot be set up between every pair of nodes. In this paper we present an improved lower bound for maximum congestion on any link In the logical topology. The bound is shown to be up to 50% higher than the existing ones. An analytical model for obtaining the maximum and average logical connection loads for a given logical network and traffic demand matrix is also formulated, and it has been confirmed via simulation. Finally, two heuristic algorithms for constructing a logical topology that reduces maximum logical connection congestion are presented.

Millimeter wave-induced vibrational modes in DNA as a possible alternative to animal tests to probe for carcinogenic mutations

Abstract: Developing methods for alternative testing is increasingly important due to dwindling funding resources and increasing costs associated with animal testing and legislation. We propose to test the feasibility of a new and novel method for detecting DNA mutagenesis using millimeter wave spectroscopy. Although millimeter wave spectroscopy has been known since the 1950s, the cost was prohibitive and studies did not extend to large biological proteins such as DNA. Recent advances have made this technology feasible for developing laboratory and field equipment. We present preliminary findings for lesion-induced vibrational modes in DNA observed from 80 to 1000 gigahertz (GHz). These findings suggest that there are vibrational modes that can be used as identification resonances. These modes are associated with localized defects of the DNA polymers. They are unique for each defect/lesion, and should be easy to detect. We described a field-detecting detector based on the local modes.

Cloning template design of cellular neural networks for associative memories

Abstract: This brief presents a synthesis procedure (design algorithm) for cellular neural networks with space-invariant cloning template with applications to associative memories. The design algorithm makes it possible to determine in a systematic manner cloning templates for cellular neural networks with or without symmetry constraints on the interconnection weights. Two specific examples are included to demonstrate the applicability of the methodology developed herein.

Nonlinear acoustic waves in porous media in the context of Biot's theory.

Abstract: The nonlinear dynamic equations introduced by Biot to model porous media have not been implemented to describe nonlinear acoustic waves in such media. In this work the equations are revised and a mathematical model depicting the physical nonlinearity is established. A perturbation technique is then applied to find solutions to the nonlinear Biot equations. An important feature of the developed model is the introduction of the dependence of the structural parameters of the medium on its porosity. The model establishes a correlation between the measurable effective nonlinear parameter and structural parameters of the porous medium. This suggests employing nonlinear measurements as a diagnostic tool for porous media.