Showing papers by "Missouri University of Science and Technology published in 2005"

Survey of clustering algorithms

Abstract: Data analysis plays an indispensable role for understanding various phenomena. Cluster analysis, primitive exploration with little or no prior knowledge, consists of research developed across a wide variety of communities. The diversity, on one hand, equips us with many tools. On the other hand, the profusion of options causes confusion. We survey clustering algorithms for data sets appearing in statistics, computer science, and machine learning, and illustrate their applications in some benchmark data sets, the traveling salesman problem, and bioinformatics, a new field attracting intensive efforts. Several tightly related topics, proximity measure, and cluster validation, are also discussed.

Guide for the Design and Construction of Concrete Reinforced with FRP Bars (ACI 440.1R-03)

Abstract: This paper reports on the key features of the “Guide for the Design and Construction of Concrete Reinforced with FRP Bars” issued by the American Concrete Institute (ACI). For new construction, FRP bars have been used as the internal reinforcement in concrete members to replace conventional steel rebars for a host of reasons. The principles for design and construction were first established and proposed to industry in 2001. The third revision of the guide is now under preparation.

Modeling cascading failures in the North American power grid

Abstract: The North American power grid is one of the most complex technological networks, and its interconnectivity allows both for long-distance power transmission and for the propagation of disturbances. We model the power grid using its actual topology and plausible assumptions about the load and overload of transmission substations. Our results indicate that the loss of a single substation can result in up to $25\%$ loss of transmission efficiency by triggering an overload cascade in the network. The actual transmission loss depends on the overload tolerance of the network and the connectivity of the failed substation. We systematically study the damage inflicted by the loss of single nodes, and find three universal behaviors, suggesting that $40\%$ of the transmission substations lead to cascading failures when disrupted. While the loss of a single node can inflict substantial damage, subsequent removals have only incremental effects, in agreement with the topological resilience to less than $1\%$ node loss.

Synthesis of a stable compound with fivefold bonding between two chromium(I) centers.

Abstract: Although in principle transition metals can form bonds with six shared electron pairs, only quadruply bonded compounds can be isolated as stable species at room temperature. Here we show that the reduction of {Cr(mu-Cl)Ar'}2 [where Ar' indicates C6H3-2,6(C6H3-2,6-Pri2)2 and Pr indicates isopropyl] with a slight excess of potassium graphite has produced a stable compound with fivefold chromium-chromium (Cr-Cr) bonding. The very air- and moisture-sensitive dark red crystals of Ar'CrCrAr' were isolated with greater than 40% yield. X-ray diffraction revealed a Cr-Cr bond length of 1.8351(4) angstroms (where the number in parentheses indicates the standard deviation) and a planar transbent core geometry. These data, the structure's temperature-independent paramagnetism, and computational studies support the sharing of five electron pairs in five bonding molecular orbitals between two 3d5 chromium(I) ions.

The use of data mining and neural networks for forecasting stock market returns

Abstract: It has been widely accepted by many studies that non-linearity exists in the financial markets and that neural networks can be effectively used to uncover this relationship. Unfortunately, many of these studies fail to consider alternative forecasting techniques, the relevance of input variables, or the performance of the models when using different trading strategies. This paper introduces an information gain technique used in machine learning for data mining to evaluate the predictive relationships of numerous financial and economic variables. Neural network models for level estimation and classification are then examined for their ability to provide an effective forecast of future values. A cross-validation technique is also employed to improve the generalization ability of several models. The results show that the trading strategies guided by the classification models generate higher risk-adjusted profits than the buy-and-hold strategy, as well as those guided by the level-estimation based forecasts of the neural network and linear regression models.

Agile Modeling, Agile Software Development, and Extreme Programming: The State of Research

Abstract: While there are many claims for the successful use of extreme programming (XP) and agile modeling (AM), and the proponents can often be vocal in the extreme regarding their supposed benefits, research evidence supporting proponents‘ claims is somewhat lacking. Currently, the only research appearing to investigate the phenomena consists of two prominent streams. A small number of case studies and experience reports that generally promote the success of XP in various development environments, and a well-established stream of research into pair programming has generated results that in part support the idea of XP. Research into AM appears to be even more sparse than that for XP. Case studies, comparative analyses, and experience reports comprise the majority of the research in the area, while very few empirical research efforts have been conducted. This article reviews the state of research in XP and AM, and recommends areas that could benefit from further study. Since nearly all empirical XP research relates to pair programming, a closer look into the unstudied XP core practices would be beneficial, although interaction between related core practice areas could confound such efforts. It might also be possible to group related core XP concepts and study the groups individually. Finally, there are those who claim that XP and AM, or even agility in general, are really nothing more than a repackaging of old concepts. This claim needs to be investigated.

One-pot Synthesis of Polyaniline-metal Nanocomposites

Abstract: Composite materials consisting of polyaniline nanofibers decorated with noble-metal (Ag or Au) nanoparticles were synthesized with γ radiolysis. Aqueous solutions of aniline, a free-radical oxidant, and/or a metal salt were irradiated with γ rays. Exposure of the solutions to γ rays caused aniline to polymerize as very-thin fibers. Metal particles were also formed during irradiation and decorated the fibers. The shape and size of the metal particles could be changed from nanometer-sized spheres to micron-sized dendrites by varying the ratio of aniline to the metal precursor. Polyaniline-metal composites were characterized using UV−Vis spectroscopy, infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The electrical conductivity of the composites increased with the loading of metal in the nanocomposites and was up to 50 times greater than that of polyaniline fibers alone.

Improved Two-Temperature Model and Its Application in Ultrashort Laser Heating of Metal Films

Abstract: The two-temperature model has been widely used to predict the electron and phonon temperature distributions in ultrashort laser processing of metals. However, estimations of some important thermal and optical properties in the existing two-temperature model are limited to low laser fluences in which the electron temperatures are much lower than the Fermi temperature. This paper extends the existing two-temperature model to high electron temperatures by using full-run quantum treatments to calculate the significantly varying properties, including the electron heat capacity, electron relaxation time, electron conductivity, reflectivity, and absorption coefficient. The proposed model predicts the damage thresholds more accurately than the existing model for gold films when compared with published experimental results.

Evolution of in Situ Refractories in the 20th Century

Abstract: A common theme over the past 100 years in refractories science and technology has been to generate a protective refractories layer in a high-temperature container, often by reaction of the refractory materials with the contents (glass, slag, or atmosphere). The history of refractories during the 20th century is used in this review to illustrate how techniques-such as slag splashing, in situ spinel generation in castables, magnesia dense layer formation in magnesia-carbon brick in steelmaking, clinker adhesion in cement kilns, and viscous boundary layer generation in glass tanks-have evolved to their present status.

Automatic lesion boundary detection in dermoscopy images using gradient vector flow snakes.

Abstract: Dermoscopy, otherwise known as skin-surface microscopy or dermatoscopy was originally introduced in 1921 (1) and reintroduced in 1987 (2). One common form of dermoscopy integrates oil immersion under glass with standard × 10 magnifying optics and incident surface lighting permit in vivo visualization of certain features of pigmented melanocytic neoplasms that cannot be observed by visual inspection. Dermoscopy using various rule- or feature-based schemes improves pigmented lesion diagnostic accuracy over the accuracy obtained without this aid for those dermatologists trained in the technique (3–8). Accurate segmentation of the lesion from the background skin is important for computer-assisted diagnostic techniques, both for the determination of lesion shape and lesion color, compared with the color of the surrounding skin (9). In this paper, a method of automatic lesion boundary detection using gradient vector flow (GVF) snakes is presented. Snakes can be defined as curves within an image domain that can move under the influence of internal forces defined within the curve, from features such as smoothness, and external forces computed from the image data (10). Snake algorithms are often sensitive to initialization for effective object segmentation. Initial points for a snake algorithm can be selected by an operator or automatically determined. For this research, an automatic initialization method is used to select an initial set of skin lesion border points for the dermoscopy image data set examined. The remainder of this paper is organized as follows. In the following section, an overview of traditional snake algorithms is presented, along with limitations of traditional snakes in the domain of pigmented images. In the third section, GVF snakes are presented. In the fourth section, the application of GVF snakes for skin lesion border determination in dermoscopy images is given. The automatic initialization method and the two-step operation of GVF snakes are described. In the fifth section, experimental results and discussion are presented comparing the GVF snake algorithm and its comparison with the histogram analysis technique developed by Pagadala (11). Finally, conclusions from this research are provided.

Harmony search for generalized orienteering problem: best touring in China

Abstract: In order to overcome the drawbacks of mathematical optimization techniques, soft computing algorithms have been vigorously introduced during the past decade. However, there are still some possibilities of devising new algorithms based on analogies with natural phenomena. A nature-inspired algorithm, mimicking the improvisation process of music players, has been recently developed and named Harmony Search (HS). The algorithm has been successfully applied to various engineering optimization problems. In this paper, the HS was applied to a TSP-like NP-hard Generalized Orienteering Problem (GOP) which is to find the utmost route under the total distance limit while satisfying multiple goals. Example area of the GOP is eastern part of China. The results of HS showed that the algorithm could find good solutions when compared to those of artificial neural network.

How much particle surface corrugation is sufficient to improve aerosol performance of powders

Abstract: Purpose. The current study aimed to quantify the different degree of particle surface corrugation and correlate it to the aerosol performance of powders.

How Generic Scale Invariance Influences Quantum and Classical Phase Transitions

Abstract: This review discusses a paradigm that has become of increasing importance in the theory of quantum phase transitions, namely, the coupling of the order-parameter fluctuations to other soft modes and the resulting impossibility of constructing a simple Landau-Ginzburg-Wilson theory in terms of the order parameter only. The soft modes in question are manifestations of generic scale invariance, i.e., the appearance of long-range order in whole regions in the phase diagram. The concept of generic scale invariance and its influence on critical behavior is explained using various examples, both classical and quantum mechanical. The peculiarities of quantum phase transitions are discussed, with emphasis on the fact that they are more susceptible to the effects of generic scale invariance than their classical counterparts. Explicit examples include the quantum ferromagnetic transition in metals, with or without quenched disorder; the metal-superconductor transition at zero temperature; and the quantum antiferromagnetic transition. Analogies with classical phase transitions in liquid crystals and classical fluids are pointed out, and a unifying conceptual framework is developed for all transitions that are influenced by generic scale invariance.

The ZrB2 Volatility Diagram

Abstract: A volatility diagram was calculated for temperatures of 1000, 1800, and 2500 K to understand the oxidation of ZrB2. Applying the diagram, it can be seen that exposure of ZrB2 to air produces ZrO2 (cr) and B2O3 (l) over the temperature range considered. The pressure of the predominant vapor species was predicted to increase from ∼10−6 Pa at 1000 K, to 344 Pa at 1800 K, and to ∼105 Pa at 2500 K. Predictions were consistent with experimental observations that ZrB2 exhibits passive oxidation below 1200 K, but undergoes active oxidation at higher temperatures due to B2O3 (l) evaporation.

The function-failure design method

Abstract: To succeed in the product development market today, firms must quickly and accurately satisfy customer needs while designing products that adequately accomplish their desired functions with a minimum number of failures. When failure analysis and prevention are coupled with a product's design from its conception, potentially shorter design times and fewer redesigns are necessary to arrive at a final product design. In this article, we explore the utility of a novel design methodology that allows failure modes and effects analysis (FMEA)-style failure analysis to be conducted during conceptual design. The function-failure design method (FFDM) guides designers towards improved designs by predicting likely failure modes based on intended product functionality.

Influence of Air Flow on the Performance of a Dry Powder Inhaler Using Computational and Experimental Analyses

Abstract: The aims of the study are to analyze the influence of air flow on the overall performance of a dry powder inhaler (Aerolizer®) and to provide an initial quantification of the flow turbulence levels and particle impaction velocities that maximized the inhaler dispersion performance. Computational fluid dynamics (CFD) analysis of the flowfield in the Aerolizer®, in conjunction with experimental dispersions of mannitol powder using a multistage liquid impinger, was used to determine how the inhaler dispersion performance varied as the device flow rate was increased. Both the powder dispersion and throat deposition were increased with air flow. The capsule retention was decreased with flow, whereas the device retention first increased then decreased with flow. The optimal inhaler performance was found at 65 l min−1 showing a high fine particle fraction (FPF) of 63 wt.% with low throat deposition (9.0 wt.%) and capsule retention (4.3 wt.%). Computational fluid dynamics analysis showed that at the critical flow rate of 65 l min−1, the volume-averaged integral scale strain rate (ISSR) was 5,400 s−1, and the average particle impaction velocities were 12.7 and 19.0 m s−1 at the inhaler base and grid, respectively. Correlations between the device flow rate and (a) the amount of throat deposition and (b) the capsule emptying times were also developed. The use of CFD has provided further insight into the effect of air flow on the performance of the Aerolizer®. The approach of using CFD coupled with powder dispersion is readily applicable to other dry powder inhalers (DPIs) to help better understand their performance optimization.

Characteristics of laser aided direct metal/material deposition process for tool steel

Abstract: Laser aided direct metal/material deposition (DMD) process builds metallic parts layer-by-layer directly from the CAD representation. In general, the process uses powdered metal/materials fed into a melt-pool, creating fully dense parts. Success of this technology in the die and tool industry depends on the parts quality to be achieved. To obtain designed geometric dimensions and material properties, delicate control of the parameters such as laser power, spot diameter, traverse speed and powder mass flow rate is critical. In this paper, the dimensional and material characteristics of directed deposited H13 tool steel by CO 2 laser are investigated for the DMD process with a feedback height control system. The relationships between DMD process variables and the product characteristics are analyzed using statistical techniques. The performance of the DMD process is examined with the material characteristics of hardness, porosity, microstructure, and composition.

Stem cell‐based composite tissue constructs for regenerative medicine

Abstract: A major task of contemporary medicine and dentistry is restoration of human tissues and organs lost to diseases and trauma. A decade-long intense effort in tissue engineering has provided the proof of concept for cell-based replacement of a number of individual tissues such as the skin, cartilage, and bone. Recent work in stem cell-based in vivo restoration of multiple tissue phenotypes by composite tissue constructs such as osteochondral and fibro-osseous grafts has demonstrated probable clues for bioengineered replacement of complex anatomical structures consisting of multiple cell lineages such as the synovial joint condyle, tendon-bone complex, bone-ligament junction, and the periodontium. Of greater significance is a tangible contribution by current attempts to restore the structure and function of multitissue structures using cell-based composite tissue constructs to the understanding of ultimate biological restoration of complex organs such as the kidney or liver. The present review focuses on recent advances in stem cell-based composite tissue constructs and attempts to outline challenges for the manipulation of stem cells in tailored biomaterials in alignment with approaches potentially utilizable in regenerative medicine of human tissues and organs.

Radiolytic synthesis of polyaniline nanofibers: A new templateless pathway

Abstract: A templateless method for the synthesis of polyaniline nanofibers and nanorods is reported which is based on gamma irradiation of aqueous solutions of aniline in the presence of an initiator.

Improving voltage stability by reactive power reserve management

Abstract: The amount of reactive reserves at generating stations is a measure of the degree of voltage stability. With this perspective, an optimized reactive reserve management scheme based on the optimal power flow is proposed. Detailed models of generator limiters, such as those for armature and field current limiting must be considered in order to utilize the maximum reactive power capability of generators, so as to meet reactive power demands during voltage emergencies. Participation factors for each generator in the management scheme are predetermined based on the voltage-var (V-Q) curve methodology. The Bender's decomposition methodology is applied to the reactive reserve management problem. The resulting effective reserves and the impact on voltage stability are studied on a reduced Western Electric Coordinating Council system. Results prove that the proposed method can improve both static and dynamic voltage stability.

Enhancing Virtual Product Representations for Advanced Design Repository Systems

Abstract: This paper describes the transformation of an existing set of heterogeneous product knowledge into a coherent design repository that supports product design knowledge archival and web-based search, display, and design model and tool generation. Guided by design theory, existing product information was analyzed and compared against desired outputs to ascertain what information management structure was needed to produce design resources pertinent to the design process. Several test products were catalogued to determine what information was essential without being redundant in representation. This set allowed for the creation of a novel single point of entry application for product information and the development of a relational database for design knowledge archival. Web services were then implemented to support design knowledge retrieval through search, browse, and real-time design tool generation. Further explored in this paper are the fundamental enabling technologies of the design repository system. Additionally, repository-generated design tools are scrutinized alongside human-generated design tools for validation. Through this process researchers have been able to improve the way in which artifact data are gathered, archived, distributed and used.

The matrix pencil for power system modal extraction

Abstract: This work introduces the matrix pencil modal extraction method through the use of several illustrative examples. This method is used to estimate the eigenvalues of reduced-order models of large nonlinear systems based on their dynamic responses.

Antitumor metallothiosemicarbazonates: structure and antitumor activity of palladium complex of phenanthrenequinone thiosemicarbazone.

Abstract: The crystal structure of the potential antitumor metal compound, viz. chloro, mono(phenanthrenequinone thiosemicarbazonato) palladium(II) dimethyl formamide solvate, is reported. The central palladium(II) atom is in a square planar environment provided by the tridentate, monoanionic thiosemicarbazone ligand and the ancillary chloride ion. The compound exhibited remarkable activity against drug-sensitive and drug-resistant breast cancer cell lines and was relatively nontoxic toward the normal mammary epithelial cells. The drug-induced killing effect against breast cancer cell lines was predominantly mediated via apoptosis, a physiologic form of cell death.

Collaborative Reliability Analysis under the Framework of Multidisciplinary Systems Design

Abstract: Traditional Multidisciplinary Design Optimization (MDO) generates deterministic optimal designs, which are frequently pushed to the limits of design constraint boundaries, leaving little or no room to accommodate uncertainties in system input, modeling, and simulation. As a result, the design solution obtained may be highly sensitive to the variations of system input which will lead to performance loss and the solution is often risky (high likelihood of undesired events). Reliability-based design is one of the alternative techniques for design under uncertainty. The natural method to perform reliability analysis in multidisciplinary systems is the all-in-one approach where the existing reliability analysis techniques are applied directly to the system-level multidisciplinary analysis. However, the all-in-one reliability analysis method requires a double loop procedure and therefore is generally very time consuming. To improve the efficiency of reliability analysis under the MDO framework, a collaborative reliability analysis method is proposed in this paper. The procedure of the traditional Most Probable Point (MPP) based reliability analysis method is combined with the collaborative disciplinary analyses to automatically satisfy the interdisciplinary consistency when conducting reliability analysis. As a result, only a single loop procedure is required and all the computations are conducted concurrently at the individual discipline-level. Compared with the existing reliability analysis methods in MDO, the proposed method is efficient and therefore provides a cheaper tool to evaluate design feasibility in MDO under uncertainty. Two examples are used for the purpose of verification.