Showing papers by "University of Illinois at Urbana–Champaign published in 1996"

Exceptionally high Young's modulus observed for individual carbon nanotubes

Abstract: CARBON nanotubes are predicted to have interesting mechanical properties—in particular, high stiffness and axial strength—as a result of their seamless cylindrical graphitic structure1–5. Their mechanical properties have so far eluded direct measurement, however, because of the very small dimensions of nanotubes. Here we estimate the Young's modulus of isolated nanotubes by measuring, in the transmission electron microscope, the amplitude of their intrinsic thermal vibrations. We find that carbon nanotubes have exceptionally high Young's moduli, in the terapascal (TPa) range. Their high stiffness, coupled with their low density, implies that nanotubes might be useful as nanoscale fibres in strong, lightweight composite materials.

A tutorial on visual servo control

Abstract: This article provides a tutorial introduction to visual servo control of robotic manipulators. Since the topic spans many disciplines our goal is limited to providing a basic conceptual framework. We begin by reviewing the prerequisite topics from robotics and computer vision, including a brief review of coordinate transformations, velocity representation, and a description of the geometric aspects of the image formation process. We then present a taxonomy of visual servo control systems. The two major classes of systems, position-based and image-based systems, are then discussed in detail. Since any visual servo system must be capable of tracking image features in a sequence of images, we also include an overview of feature-based and correlation-based methods for tracking. We conclude the tutorial with a number of observations on the current directions of the research field of visual servo control.

Employee Creativity: Personal and Contextual Factors at Work

Abstract: This study examined the independent and joint contributions of employees' creativity-relevant personal characteristics and three characteristics of the organizational context—job complexity, suppor...

Nitrogen - inorganic forms.

Abstract: Most soils contain inorganic nitrogen (N) in the form of ammonium (NHt) and nitrate (NO)"). Nitrite (NOz) also may be present, but the amount is usually too small to warrant its determination, except in cases where NHt or NHt-forming fertilizers are applied to neutral or alkaline soils. Several other forms of inorganic N have been proposed as intermediates during microbial transformations of N in soils, including hydroxylamine (NH20H), hyponitrous acid (H2N20 2), and nitramide (NH2N02), but these compounds are thermodynamically unstable and have not been detected in soil. Until the 1950s, inorganic N was believed to account for <2% of total soil N, on the assumption that NHt and NO)" are completely recovered by extracting soil with a neutral salt solution. The validity of this assumption was challenged by the finding that some soils contain NHt in a form that is not extracted by exchange with other cations (e.g., Rodrigues, 1954; Dhariwal & Stevenson, 1958; Stevenson & Dhariwal, 1959; Bremner & Harada, 1959; Bremner, 1959; Schachtschabel, 1960, 1961; Young, 1962), and by estimates that the proportion of soil N in this form can exceed 50% for some subsurface soils (Stevenson & Dhariwal, 1959; Young, 1962). In such cases, NHt is said to be fixed, and fixed NHt has subsequently been defined as the NHt in soil that cannot be replaced by a neutral potassium salt solution (SSSA, 1987), such as 1 or 2 M KCI or 0.5 M K2S04, in contrast to exchangeable NHt, which is extractable at room temperature with such a solution. Existing information indicates that fixed NHt occurs largely, if not entirely, between the layers of 2: I-type clay minerals, particularly vermiculite and illite (hydrous mica), and that fixation results from entrapment of NHt in ditrigonal voids in the exposed surfaces upon contraction of the clay lattice (Nommik & Vahtras, 1982). The term, nonexchangeable NHt, has been used by Bremner (1965) and Keeney and Nelson (1982) in previous editions of this publication as a more precise alternative to fixed NHt. The same term is used in the present treatment, with specific reference to NHt determined by the method described in "Determination of Nonexchangeable Ammonium," which involves digestion with an HF-HCI solution following treatment of the soil with alkaline KOBr to remove exchangeable NHt and labile organic-N compounds.

Steps Toward an Ecology of Infrastructure: Design and Access for Large Information Spaces

Abstract: We analyze a large-scale custom software effort, the Worm Community System (WCS), a collaborative system designed for a geographically dispersed community of geneticists. There were complex challenges in creating this infrastructural tool, ranging from simple lack of resources to complex organizational and intellectual communication failures and tradeoffs. Despite high user satisfaction with the system and interface, and extensive user needs assessment, feedback, and analysis, many users experienced difficulties in signing on and use. The study was conducted during a time of unprecedented growth in the Internet and its utilities (1991–1994), and many respondents turned to the World Wide Web for their information exchange. Using Bateson's model of levels of learning, we analyze the levels of infrastructural complexity involved in system access and designer-user communication. We analyze the connection between systems development aimed at supporting specific forms of collaborative knowledge work, local orga...

Self-consistent order- N density-functional calculations for very large systems

Abstract: We present a method to perform fully self-consistent density-functional calculations that scales linearly with the system size and which is well suited for very large systems. It uses strictly localized pseudoatomic orbitals as basis functions. The sparse Hamiltonian and overlap matrices are calculated with an $O(N)$ effort. The long-range self-consistent potential and its matrix elements are computed in a real-space grid. The other matrix elements are directly calculated and tabulated as a function of the interatomic distances. The computation of the total energy and atomic forces is also done in $O(N)$ operations using truncated, Wannier-like localized functions to describe the occupied states, and a band-energy functional which is iteratively minimized with no orthogonality constraints. We illustrate the method with several examples, including carbon and silicon supercells with up to 1000 Si atoms and supercells of $\ensuremath{\beta}$-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$. We apply the method to solve the existing controversy about the faceting of large icosahedral fullerenes by performing dynamical simulations on ${\mathrm{C}}_{60}$, ${\mathrm{C}}_{240}$, and ${\mathrm{C}}_{540}$.

Modularity, flexibility, and knowledge management in product and organization design

Abstract: This pczper investigcztes irzterrelationslzi~~s of product design, orgcznization design, processes for leartlirzg and managing knowledge, arzd competitive strategy. This paper uses the principles of nearly decotnposable systems to investigate the ability of strind(irdized interfcices between components in cz product design to embed coordination of product development processes. Embedded coordination creates 'hierczrchical coordination' without the need to continually exercise authority-erzcrblirlg effective coordination of processes without the tight coupling of orgcznizationczl structures. We develop concepts of modularity in product and organization designs based orz smndcirdized component and organization interjczces. Modular product architec- tures create information structures that provide the 'glue' that holds together the loosely coupled parts of a modular orgatzizatiorz design. By fczcilitriting loose coupling, modularity can czlso reduce the cost and dyficulty of adaptive coordination, thereby incrensing the strategic flexibility of firms to respond to erzvironmentnl change. Modularity in product and organizcztion designs therefore etznbles cz new strcitegic approach to the management of knowledge based on cztz irztentionczl, carefully mcznaged loose coupling of (I firm's learning processes czt architec- tural cznd comporzent levels of product crecztiorz processes.

Mathematical Programs with Equilibrium Constraints

Abstract: This book provides a solid foundation and an extensive study for an important class of constrained optimization problems known as Mathematical Programs with Equilibrium Constraints (MPEC), which are extensions of bilevel optimization problems. The book begins with the description of many source problems arising from engineering and economics that are amenable to treatment by the MPEC methodology. Error bounds and parametric analysis are the main tools to establish a theory of exact penalisation, a set of MPEC constraint qualifications and the first-order and second-order optimality conditions. The book also describes several iterative algorithms such as a penalty-based interior point algorithm, an implicit programming algorithm and a piecewise sequential quadratic programming algorithm for MPECs. Results in the book are expected to have significant impacts in such disciplines as engineering design, economics and game equilibria, and transportation planning, within all of which MPEC has a central role to play in the modelling of many practical problems.

Social Information‐Processing Mechanisms in Reactive and Proactive Aggression

Abstract: Theories of aggressive behavior and ethological observations in animals and children suggest the existence of distinct forms of reactive (hostile) and proactive (instrumental) aggression. Toward the validation of this distinction, groups of reactive aggressive, proactive aggressive, and nonaggressive children were identified (n = 624 9-12-year-olds). Social information-processing patterns were assessed in these groups by presenting hypothetical vignettes to subjects. 3 hypotheses were tested: (1) only the reactive-aggressive children would demonstrate hostile biases in their attributions of peers' intentions in provocation situations (because such biases are known to lead to reactive anger); (2) only proactive-aggressive children would evaluate aggression and its consequences in relatively positive ways (because proactive aggression is motivated by its expected external outcomes); and (3) proactive-aggressive children would select instrumental social goals rather than relational goals more often than nonaggressive children. All 3 hypotheses were at least partially supported.

Discriminant validity of well-being measures.

Abstract: The convergent and discriminant validities of well-being concepts were examined using multitrait-multimethod matrix analyses (D. T. Campbell & D. W. Fiske, 1959) on 3 sets of data. In Study 1, participants completed measures of life satisfaction, positive affect, negative affect, self-esteem, and optimism on 2 occasions 4 weeks apart and also obtained 3 informant ratings. In Study 2, participants completed each of the 5 measures on 2 occasions 2 years apart and collected informant reports at Time 2. In Study 3, participants completed 2 different scales for each of the 5 constructs. Analyses showed that (a) life satisfaction is discriminable from positive and negative affect, (b) positive affect is discriminable from negative affect, (c) life satisfaction is discriminable from optimism and self-esteem, and (d) optimism is separable from trait measures of negative affect.

Pattern-Oriented Software Architecture

Abstract: ion and object-oriented organization, Event-based, implicit invocation Pattern-Oriented Software Architecture, A System of Patterns Volume 1 – Frank. Format: pdf Pattern-Oriented Software Architecture Volume 1: A System of Patterns by Frank Buschmann, Regine Meunier, Hans Rohnert and Peter. Full Text: PDF Volume 40 Issue 1, January 2015 Service-Oriented Architecture is an architectural style where different heterogeneous components share Robert Hanmer, Patterns for Fault Tolerant Software, Wiley Publishing, 2007. 11. Pattern-Oriented Software Architecture Volume 1: A System of Patterns, Pattern,Oriented Pattern oriented software architecture pdf free download – i6fw9. Robert Hanmer, "Pattern-oriented Software Architecture For Dummies" 2013 / ISBN-10: 1119963990 / 384 pages / PDF / 31 MB Science, Engineering and Applications", volume 1 ed. by David C. Wyld, Jan Zizka, Dhinaharan Nagamalai Kumar Saurabh Singh 1,*, Dominique Thual 2, Roberto Spurio 1 and Nicola information management is important especially when a large volume of F., Meunier, R., Rohnert, H. Pattern-Oriented Software Architecture: A System. Pattern-Oriented Software Architecture Volume 2 Patterns for Concurrent and Networked Architecture Volume 2 Patterns for Concurrent and Networked Objects.pdf: Sponsored Link udp://tracker.coppersurfer.tk:6969/announce: 2 hours 0 1. extend the usability of any software system we have high degree of user Architectural patterns (1) provide structural notations for any software system. In spite of abundant tools and literature about mobile educational software, the lake of a This study uses design patterns to present platform independent architecture to support Enter the password to open this PDF file: Pattern-Oriented Software Architecture, Volume 1: A System of References (19), Cited In (1). What software architecture is and what it is not, Other points of view, Stal: Pattern-Oriented Software Architecture, A System of Patterns, Volume 1, John. Frank Buschmann: Pattern-Oriented Software Architecture Volume 4: A Pattern Language for Distributed Computing. Download PDF MOBi EPUB Kindle.

The Psychological Measurement of Cultural Syndromes.

Abstract: An examination of a range of definitions of culture indicates that almost all researchers agree that culture is reflected in shared cognitions, standard operating procedures, and unexamined assumptions. Cultural syndromes consist of shared attitudes, beliefs, norms, role and self definitions, and va

LOGIT MODELS AND LOGISTIC REGRESSIONS FOR SOCIAL NETWORKS: I. AN INTRODUCTION TO MARKOV GRAPHS AND p*

Abstract: Spanning nearly sixty years of research, statistical network analysis has passed through (at least) two generations of researchers and models. Beginning in the late 1930's, the first generation of research dealt with the distribution of various network statistics, under a variety of null models. The second generation, beginning in the 1970's and continuing into the 1980's, concerned models, usually for probabilities of relational ties among very small subsets of actors, in which various simple substantive tendencies were parameterized. Much of this research, most of which utilized log linear models, first appeared in applied statistics publications. But recent developments in social network analysis promise to bring us into a third generation. The Markov random graphs of Frank and Strauss (1986) and especially the estimation strategy for these models developed by Strauss and Ikeda (1990; described in brief in Strauss, 1992), are very recent and promising contributions to this field. Here we describe a large class of models that can be used to investigate structure in social networks. These models include several generalizations of stochastic blockmodels, as well as models parameterizing global tendencies towards clustering and centralization, and individual differences in such tendencies. Approximate model fits are obtained using Strauss and Ikeda's (1990) estimation strategy. In this paper we describe and extend these models and demonstrate how they can be used to address a variety of substantive questions about structure in social networks.

Most People Are Happy

Abstract: Myers and Diener (1995) asked “Who is happy?” but examined the question of who is more and who is less happy In fact, most people report a positive level of subjective well-being (SWB), and say that they are satisfied with domains such as marriage, work, and leisure People in disadvantaged groups on average report positive well-being, and measurement methods in addition to self-report indicate that most people's affect is primarily pleasant Cross-national data suggest that there is a positive level of SWB throughout the world, with the possible exception of very poor societies In 86% of the 43 nations for which nationally representative samples are available the mean SWB response was above neutral Several hypotheses to explain the positive levels of SWB are discussed

Spectroscopic evidence for a pseudogap in the normal state of underdoped high- T c superconductors

Abstract: IT is well known that BCS mean-field theory is remarkably successful in describing conventional superconductors. A central concept of BCS theory is the energy gap in the electronic excitation spectrum below the superconducting transition temperature, Tc. The gap also serves as the order parameter: quite generally, long-range phase coherence and a non-zero gap go hand-in-hand1. But in underdoped high-Tc superconductors there is considerable evidence that a pseudogap (a suppression of spectral weight) is already formed in the normal state above Tc—first, from studies of the spin excitation spectrum2–5,24, which measure a 'spin gap', and later from a variety of other probes6–10. Here we present a study of underdoped Bi2Sr2CaCu2O8+δ (Bi2212) using angle-resolved photoemission spectroscopy (ARPES), which directly measures the momentum-resolved electron excitation spectrum of the CuO2 planes. We find that a pseudogap with d-wave symmetry opens up in the normal state below a temperature T* > Tc, and develops into the d-wave superconducting gap once phase coherence is established below Tc.

Children's treatment by peers: Victims of relational and overt aggression

Abstract: Past research on peer victimization has focused on maltreatment through overtly aggressive behaviors. Although a relational form of aggression has been identified in recent research, studies of the victims of relational aggression have not yet been conducted. The present research was designed as a first attempt to address this issue. Four goals were pursued (n = 474; third- through sixth-grade children): (a) development of a self-report measure of victimization through relational and overt aggression; (b) assessment of the relation between overt victimization and relational victimization; (c) assessment of gender, grade, and sociometric status group differences in victimization; and (d) evaluation of the relation between victimization and social-psychological adjustment. Results showed that the newly developed victimization measure had favorable psychometric properties and that most of the identified victims were the targets of cither relational or overt aggression, but not both. Further, rejected children were more relationally and overtly victimized than their better accepted peers, and boys were more overtly victimized than girls. Finally, relational victimization, overt victimization, and the lack of prosocial treatment by peers were all significantly related to social-psychological adjustment difficulties (e.g., depression, loneliness).

Niching methods for genetic algorithms

Abstract: Niching methods extend genetic algorithms to domains that require the location and maintenance of multiple solutions. Such domains include classification and machine learning, multimodal function optimization, multiobjective function optimization, and simulation of complex and adaptive systems. This study presents a comprehensive treatment of niching methods and the related topic of population diversity. Its purpose is to analyze existing niching methods and to design improved niching methods. To achieve this purpose, it first develops a general framework for the modelling of niching methods, and then applies this framework to construct models of individual niching methods, specifically crowding and sharing methods. Using a constructed model of crowding, this study determines why crowding methods over the last two decades have not made effective niching methods. A series of tests and design modifications results in the development of a highly effective form of crowding, called deterministic crowding. Further analysis of deterministic crowding focuses upon the distribution of population elements among niches, that arises from the combination of crossover and replacement selection. Interactions among niches are isolated and explained. The concept of crossover hillclimbing is introduced. Using constructed models of fitness sharing, this study derives lower bounds on the population size required to maintain, with probability $\gamma$, a fixed number of desired niches. It also derives expressions for the expected time to disappearance of a desired niche, and relates disappearance time to population size. Models are presented of sharing under selection, and sharing under both selection and crossover. Some models assume that all niches are equivalent with respect to fitness. Others allow niches to differ with respect to fitness. Focusing on the differences between parallel and sequential niching methods, this study compares and further examines four niching methods--crowding, sharing, sequential niching, and parallel hillclimbing. The four niching methods undergo rigorous testing on optimization and classification problems of increasing difficulty; a new niching-based technique is introduced that extends genetic algorithms to classification problems.

k⋅p method for strained wurtzite semiconductors

Abstract: We derive the effective-mass Hamiltonian for wurtzite semiconductors, including the strain effects. This Hamiltonian provides a theoretical groundwork for calculating the electronic band structures and optical constants of bulk and quantum-well wurtzite semiconductors. We apply Kane's model to derive the band-edge energies and the optical momentum-matrix elements for strained wurtzite semiconductors. We then use the k\ensuremath{\cdot}p perturbation method to derive the effective-mass Hamiltonian, which is then checked with that derived using an invariant method based on the Pikus-Bir model. We obtain the band structure ${\mathit{A}}_{\mathit{i}}$ parameters in the group theoretical model explicitly in terms of the momentum-matrix elements. We also find the proper definitions of the important physical quantities used in both models and present analytical expressions for the valence-band dispersions, the effective masses, and the interband optical-transition momentum-matrix elements near the band edges, taking into account the strain effects. \textcopyright{} 1996 The American Physical Society.

Teaching Students to Generate Questions: A Review of the Intervention Studies

Abstract: This is a review of intervention studies in which students have been taught to generate questions as a means of improving their comprehension. Overall, teaching students the cognitive strategy of generating questions about the material they had read resulted in gains in comprehension, as measured by tests given at the end of the intervention. All tests were based on new material. The overall median effect size was 0.36 (64th percentile) when standardized tests were used and 0.86 (81st percentile) when experimenter-developed comprehension tests were used. The traditional skill-based instructional approach and the reciprocal teaching approach yielded similar results.

Peer victimization : Cause or consequence of school maladjustment?

Abstract: Past research has shown that peer victimization and school maladjustment are related, but it is unclear whether victimization is a cause or consequence of such difficulties. This study examined whether (a) peer victimization is a precursor of school maladjustment, (b) the effects are limited to the period of victimization, and (c) stable peer victimization experiences compound adjustment difficulties. Toward this end, data were collected on 200 5- and 6-year-old children (105 males, 95 females) in the fall and spring of kindergarten. Findings supported the hypothesis that victimization is a precursor of children's loneliness and school avoidance. Whereas children's feelings of loneliness were more pronounced while victimization was occurring, delayed effects were found for school avoidance. Furthermore, the duration of children's victimization experiences was related to the magnitude of their school adjustment problems.

Changes in Adolescents: Daily Interactions with Their Families from Ages 10 to 18: Disengagement and Transformation.

Abstract: In a cross-sequential study spanning 5th-12th grade, 220 White working-and middle-class youth provided reports on their experience at 16,477 random moments in their lives. Amount of time spent with family was found to decrease from 35% to 14% ofwaking hours across this age period. indicating disengagement. However, transformation and continued connection were evident in stability across age in time talking and alone with parents; an age increase in family conversation about interpersonal issues, particularly for girls; and with age, adolescents' more frequent perception of themselves as leading interactions. After a decrease in early adolescence, older teens reported more favorable affect in themselves and others during family interactions. Last, the age decline in family time was found to be mediated not by internal family conflict but by opportunities and pulls an adolescent experiences from outside the family.

Size-Dependent Melting Properties of Small Tin Particles: Nanocalorimetric Measurements.

Abstract: For the first time, the latent heat of fusion $\ensuremath{\Delta}{H}_{m}$ for Sn particles formed by evaporation on inert substrate with radii ranging from 5 to 50 nm has been measured directly using a novel scanning nanocalorimeter. A particle-size-dependent reduction of $\ensuremath{\Delta}{H}_{m}$ has been observed. An ``excluded volume'' is introduced to describe the latent heat of fusion from the enhanced surface melting of small particles. Melting point depression has also been found by our nanocalorimetric technique.

Insult, Aggression, and the Southern Culture of Honor: An "Experimental Ethnography"

Abstract: Three experiments examined how norms characteristic of a "culture of honor" manifest themselves in the cognitions, emotions, behaviors, and physiological reactions of southern White males. Participants were University of Michigan students who grew up in the North or South. In 3 experiments they were insulted by a confederate who bumped into the participant and called him an "asshole". Compared with northerners--who were relatively unaffected by the insult--southerners were (a) more likely to think their masculine reputation was threatened, (b) more upset (as shown by a rise in cortisol levels), (c) more physiologically primed for aggression (as shown by a rise in testosterone levels), (d) more cognitively primed for aggression, and (e) more likely to engage in aggressive and dominant behavior. Findings highlight the insult-aggression cycle in cultures of honor, in which insults diminish a man's reputation and he tries to restore his status by aggressive or violent behavior.