bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance and Satisfaction in Private versus Nonprivate Work Settings
Authors: Block Lisa K. , Stokes Garnett S.
Published: March 2007

The role of individual differences, task complexity, and privacy in determining performance and environmental satisfaction was explored.Greater arousal levels in a nonprivate office were predicted to decrease satisfaction expressed for nonprivate settings but to increase performance by producing a social facilitation effect. It was proposed that sex and introversion/extroversion would interact with task complexity and privacy. Research participants were 169 introductory psychology students who were randomly placed in either private or nonprivate offices. Results indicated that greater satisfaction was expressed by those working in the private offices. In addition, people working on the complex task were more satisfied in the private setting than the nonprivate one. The social facilitation hypothesis was supported, and male introverts performed best in the nonprivate office on the simple task. Implications for organizations and for future research are discussed. Organizations vary considerably in the layout and design of their offices. However, the effects of spatial characteristics on employees in the office have only recently begun to receive attention (Wineman, 1986). One concern is whether or not the open office is an asset to the organization
A Comparative Study of a Traveling Exhibition at Four Public Settings in Canada
Authors: Rubenstein Rosalyn , Paradis Andrea , Munro Leslie
Published: March 2007

A descriptive visitor study was completed that systematically evaluated visitor response to a traveling exhibition at four settings across Canada. To allow direct comparisons, the same methods and procedures were used at all venues: Unobtrusive observations and an interviewer-administered questionnaire. In total, 668 visitors were interviewed as they exited the exhibition. Results build on and reaffirm previous studies of exhibit effectiveness conducted in a single setting. This comparative study in four venues provides further information on environmental design and exhibit effectiveness, as well as an audience profile for the exhibition. Guidelines for the development of traveling exhibitions are suggested.
Psychophysiological Characteristics Related to the Functional State of the Members of the Soviet-American Arctic Bering Bridge Expedition
Authors: Koscheyev Victor S. , Roschina Natalie A. , Makhov Vladimir V.
Published: March 2007

Psychophysiological testing was carried out on the 12 members of the Soviet-American Bering Expedition team prior to the start of the expedition and at four points along the route through the USSR. The group also completed daily ratings of anxiety, well-being, activity, and positive mood. Team members demonstrated good psychological adjustment and personality characteristics reflective of high energy levels and low depression. There were several significant differences in psychophysiological functioning in relation to ethnic or national origin groupings. Asignificantly more positive mood level and lesser situational anxiety were demonstrated in indigenous team members. Blood pressure levels assessed on males only were normal for ail members, although mean diastolic blood pressure was significantly higher in the Caucasian group. We conclude that factors of personal adjustment are important to evaluate in predicting human psychosocial behavior in extreme climatic conditions.
Factors Predicting Environmental Concern and Indifference in 13- to 16-Year-Olds
Authors: Lyons Evanthia , Breakwell Glynis M.
Published: March 2007

This study examined the relative powerof sociodemographic, knowledge, and attitudinal variables in predicting environmental concem and indifference in young people, using data from a subsample of 1,089 13- to 1 6-year-olds who participated in a U.K. survey on public understanding of science. The best discriminator between environmentally concemed and indifferent young people was self-reported level of knowledge about specific environmental issues. Level of scientific knowledge and exposure to television science programs were also powerful discriminators after the social class effect was considered. In addition, attitudes toward scientific changes were a good discriminating factor, after the effects of social class and knowledge were taken into account. However, age contributed only slightly in predicting environmental concern and indifference, and sex and personal commitment to science made no significant contribution. These findings support prior researchers' assertions that views about science relate to environmental attitudes and have implications for environmental education.
An Exploratory Study of Preferred Tree Form
Authors: Sommer Robert , Summit Joshua
Published: March 2007

Two computer-generated tree icons plus one icon copied from a nursery catalog were designed with five variations each in canopy size, trunk height, and trunk width. Seven classes of students selected the most attractive tree forms. Respondents showed a preference for larger canopies and for smaller and thinner trunks. Preferred canopy size was positively related to trunk thickness and less to trunk height. The results support the predictions of habitat theory regarding preferred tree shape and show the feasibility of using psychophysical methods to explore these issues.
Intergroup Social Relations and Architecture: Vernacular Architecture and Issues of Status, Power, and Conflict
Authors: Mazumdar Sanjoy , Mazumdar Shampa
Published: March 2007

This study examines the relationship between religion, majority-minority intergroup relations, and vernacular domestic architecture. Specifically, it looks at three facets of intergroup relations, power, status, and conflict, and their interrelationships with architecture. Through an ethnographic study focusing on the Zoroastrians, a religious minority in predominantly Muslim Iran, and their domestic architecture, we indicate how the design of the home and of the neighborhood expresses religion-related hegemonic social relations, power differentials, status distinctions, and conflict. We show that architectural features such as location, designs of houses, heights, and presence or absence of special devices, such as badgirs and "sacrificial spaces," play a part in the enaction of power, status, and conflict while forming a record of them. Architectural features can aid in the survival and preservation of a group's cultural identity, and be symbolic of resistance. We indicate how for the Zoroastrians, architecture became a means of resistance-a survival strategy-and how the home design began to incorporate fortress-like qualities to protect and preserve their unique religious identity and cultural traditions. We recommend the adoption of a socioarchitectural approach that involves simultaneous examination of both the social world and the material world, as examination of either produces an incomplete and partial picture.
The Internet: A Challenge to Public Service Broadcasting?
Authors: Hills Jill , Michalis Maria
Published: March 2007

This article attempts to fill the gap in our understanding of the strategies that public service broadcasters are utilizing in relation to the Internet. It starts therefore from a discussion of corporate strategy and of branding. There then follows a survey of public service websites, their interactivity and content. It shows that the websites of public service broadcasters vary considerably. The article concludes that, by introducing a new set of competitors, the Internet is set to increase the commercial challenge to the legitimacy of public service broadcasting and has already begun to focus demands for another review of its role.
US Media Coverage of the 1994 Elections in South Africa
Authors: Reta Meseret Chekol
Published: March 2007

Using a frame analysis technique, this article attempts to depict the way US media, represented here by the Washington Post and New York Times, presented major issues and actors in the 1994 South African elections. The data in support of the study's two hypotheses reveal that the media framed issues in such a way as to encourage negotiation, reconciliation, free and fair elections and the formation of an all-inclusive government. By contrast, the media discouraged violence, belligerence and separatism. Similarly, they projected a favorable image of South African pro-election groups or personalities, while they disfavored all forces that stood against free and fair elections and the installment of a government of national unity. Coverage was found to be reflective of American journalistic values of ethnocentricism and social order. The author concludes that the US media framed issues and actors in the South African elections based on American democratic values.
Who is the Enemy?
Authors: First Anat
Published: March 2007

This study focuses on the portrayal of Arabs in Israeli news during the beginning of the Palestinian Intifada. At that time, there was only one news television programme in Hebrew - Mabat - which was (and still is) owned by the state. This was the only source of information and images which constructed and represented Israel-Arab relations and legitimized the contemporary power structure. We have found after conducting a content analysis of 54 news broadcasts that coverage presented a negatively biased portrayal of all Arabs. Arabs tend to be underrepresented, unidentified by name or profession and engaged in oppositional activities. The coverage also distinguished the Palestinians from the other Arab groups in ways that tended to undermine or trivialize their struggle. This finding can be best understood in the context of a conflict between two nations where each is trying to draw the boundaries of its own `imagined community'.
Discourse Ethics and the Right to Communicate
Authors: Jacobson Thomas L.
Published: March 2007

Those who proposed a new `right to communicate' during the 1970s faced the challenge of defining a human right both universal and multiculturally sensitive. While progress was made, the challenge remains today. For the new right has not been enshrined in any major rights accords. Furthermore, cultural relativism is influential today, and the conflict between cultural relativism and ethical universalism is widely recognized. Jurgen Habermas's discourse ethics addresses this conflict. First, the evolution of the right to communicate is reviewed. Next follows a brief review of debates regarding universalism. Then, Habermas's discourse ethics is introduced within the framework of his theory of communicative action. Finally, parallels between discourse ethics and the right to communicate are drawn, and elements of the theory of communicative action are indicated that are pertinent to concerns about communication access and participation.
An Animated Imbalance
Authors: Cooper-Chen Anne
Published: March 2007

Along with Japanese children, other Asian children are watching such cartoon shows as Doraemon, Dragonball Z and Sailor Moon. Animated cartoons, accounting for 58.3 percent of Japan's television exports, reach Asia's large youth population, just as the birth rate in Japan is declining. In Asia, animation constitutes the largest category of children's television programming (28.4 percent) - almost all of it imported. However, cartoons do not rank high on research agendas; the girls' market is particularly neglected, even though Asian girls more than boys may receive a television `education' at home. This study found that television cartoons marketed toward boys out-number girls' cartoons by 2:1 on domestic and satellite channels. Using responses from an Internet mailing list devoted to Japanese cartoons marketed to girls, the author identified Sailor Moon as the most influential series of the 1990s. The study explored Sailor Moon as a role model as well as the heroines of programs broadcast on pan-Asia satellite services. It finds the lack of children's television imports into Japan of greater concern than the values or volume of Japan's cartoon exports to Asia.
A Multifacet Model of Organizational Learning
Authors: Lipshitz Raanan , Popper Micha , Friedman Victor J.
Published: March 2007

The objective of this article is to map the manyfacets of organizational learning into an integrative and parsimonious conceptual framework that can help researchers and practicioners identify, study, and introduce organizational learning to organizations. The article addresses the gap between theoryand practice of organizational learning byproviding a working definition of “productive organizational learning” and then describing the conditions under which organizations are likelyto learn. The model presented draws on scholarly organizational learning literature, practicioner accounts, and our own experiences as researchers and practitioners. It argues that learning by organization, as distinct from learning in organizations, requires the existence of organizational learning mechanisms. These mechanisms, which represent the “structural facet, ” are necessarybut not sufficient for generating productive organizational learning. The qualityof organizational learning depends on additional facets of organizational learning (cultural, psychological, policy, and contextual), which facilitate or inhibit learning and are also explored in this article.
Selecting Decision Rules for Crucial Choices
Authors: Nutt Paul C.
Published: March 2007

Thompson developed a framework to make strategic choices that indicates when to use optimizing, satisficing, instrumentality, and social tests as decision rules. These oft-cited prescriptions have not been empiricallyinvestigated. This studyprovides such a test by comparing the success realized when Thompson’s prescriptions were or were not followed in more than 300 strategic decisions. The findings indicate that managers followed the prescriptions in 4 of 10 decisions. Failing to follow the prescriptions led managers to applya decision rule that either developed misleading factual information or ignored available information as choices were made. Both misusing and ignoring evaluative information dramaticallylowered the prospect of success. Success improved when a decision rule was selected that adhered to the prescriptions. The implications of these findings for managers and management are discussed.
On the Detachment of the Ends of Microfibers from the Matrix Due to Tension in the Composite
Authors: Hussain M.A. , Pu S.L. , Sadowsky M.A.
Published: March 2007

The above title describes one of several ways in which a mechan ical failure of a composite has been observed to occur.

A rigid oblong elliptic shape has been chosen for the fiber in two-dimensional treatment. Analytical formulation of the problem leads to a mixed boundary value problem of the mathematical theory of elasticity.

Recent advances in reducing dual series formulations to varia tional minimization procedures (via a Fredholm integral equation of the first kind) make a mathematical analysis feasible. The variational method leads to a transcendental equation whose only real root has been evaluated by the computer for various values of the elastic constants of the matrix.

The results show a substantial destruction of the bond between matrix and fiber due to the size of the detached region which ex tends over practically one-fourth of the microfiber at each end.
Determination of Reinforcement Unbonding of Composites by a Vibration Technique
Authors: Lifshitz J.M. , Rotem A.
Published: March 2007

An experimental technique was developed to determine the condi tions for the onset of reinforcement unbonding in composite materials. The technique is based upon the continuous measurement of the dynamic moduli and damping of tensile specimens. The samples are subjected to low amplitude longitudinal and torsional oscillations superimposed on the tensile loading. Experiments were performed at room temperature on quartz particle filled resin specimens. The results for specimens with epoxy binder indicated that unbonding did not occur prior to overall failure. Those for the polyester specimens, however, showed that early particle separation occurred under certain conditions.
On the Use of Shell Theory for Determining Stresses in Composite Cylinders
Authors: Whitney J.M.
Published: March 2007

Applying Vlasov-Ambartsumyan shell theory to anisotropic and laminated cylinders, equations are developed for calculating the stresses in a composite tube under combined axial load, torsion, and internal pressure. Comparison to results obtained from exact elasticity theory shows that the shell equations are capable of predicting, with a reasonable degree of accuracy, the large stress gradients found in highly anisotropic tubes. Thus the shell theory provides the experimentalist with a set of closed form expressions for readily defining the proper specimen dimensions for precise characterization of unidirectional and laminated composite tubes. A modification to the shell theory, in which the effects of transverse normal strain are included is also discussed. Numerical results show that such a modification is necessary for determining stresses induced by free thermal expansion. It is also shown that certain classical thin shell kinematic relations are incapable of predicting stresses in composite tubes.
The Application of the Principles of Linear Elastic Fracture Mechanics to Unidirectional Fiber Reinforced Composite Materials
Authors: Wright M.A. , Iannuzzi F.A.
Published: March 2007

The strength of individual carbon fibers was measured, and the results were used to calculate the lower bound of strength expected from carbon- fiber reinforced epoxy matrix materials. Using the value of the mean stress in the fibers at fracture of a composite and the principles of linear elastic fracture mechanics, the strength of coupon specimens containing edge slots could be predicted. However, the results of some initial compliance experi ments indicated that some slight modifications of the expressions generated for isotropic pin-loaded specimens were necessary to account for the specific experimental techniques used.
Elastic Moduli of Carbon-Epoxy Composites and Carbon Fibers
Authors: Ishikawa Takashi , Koyama Kazuo , Kobayashi Shigeo
Published: March 2007

All independent elastic moduli of unidirectional carbon-epoxy com posites were measured in the tensile and torsional tests of co-axis and off-axis specimens. The experiments were motivated to estimate the unmeasurable elastic moduli of carbon fiber itself. The experimental results were incorporated with the authors' preceding analytical results which describe the relationships between the moduli of composites and consti tuents. According to several results, the fact that the hexagonal array packing is more favorable as an idealized model was obtained. It should be noted that carbon fiber is highly anisotropic and that the estimated values of those moduli are reasonable in comparison with those in a few existing references. Some of the basic assumptions employed in the analysis were confirmed by the observation of the transverse and longitudinal sections of the specimens through an electron-scanning-beam microscope (ESM).
Calculation of Edge Stresses in Multi-Layer Laminates by Sub-Structuring
Authors: Wang A.S.D. , Crossman Frank W.
Published: March 2007

A simplified method for calculating interlaminar stresses is accom plished by smearing two or more laminas as a quasi-homogeneous lamina. Numerical examples show the accuracy and the limitations of the smearing technique.
Shock Wave Propagation in Layered Composites
Authors: Oved Yoel , Luttwak Gabi E. , Rosenberg Zvi
Published: March 2007

Stress histories in multilayered composite targets were recorded using manganin gages in plane impact powder gun experiments.

The results exhibit an interesting resonance behavior due to the multiple wave reflections in the layers. This phenomenon is well known in com posites with periodic structure near the linear elastic region, but was not expected to be important at higher stresses, contrary to our results.

Elasto-plastic calculations carried out with a finite difference pseudo- viscosity hydro-code did reproduce the experimental result and helped us to better understand the mechanism of shock wave propagation in the composites.
Energy Absorption in Composite Structures
Authors: Thornton P.H.
Published: March 2007

The specific energy absorbed during the axial collapse of a variety of graphite, Kevlar and glass fiber composite tubes was determined. Although structural collapse occurred by a fracture failure mode, the specific energy absorption was higher than that of high strength metal tubes which col lapsed by buckling, over a wide range of tube geometries (t/D ratios), provided that the correct trigger mechanism was used to initiate the failure. Little change in the specific energy absorption was observed over a wide range of compression rates or with temperature changes below 20°C; above 20°C the effect of temperature varied with the resin employed. Collapse occurred initially by interlamellar shear followed by fiber fracture. The results were correlated on the basis of the specific interlamellar shear stress which permitted the energy absorption values for a variety of materials to be compared.
The Effect of Filler-Volume Fraction on Crack-Propagation Behavior of Particulate Composites
Authors: Theocaris P.S. , Papanicolaou G.C. , Papadopoulos G.A.
Published: March 2007

In the present investigation high-speed photography along with the well-known method of caustics were used for the determination of the crack-propagation velocity and the K I-stress intensity factor in iron-epoxy particulate composites. Specimens with three different low percentage filler-volume fractions were used; namely, 3%, 5% and 7%. It was found that the mean crack-propagation velocity decreases linearly with increasing filler-volume fraction. In addition, by using the method of caustics, the KI-stress intensity factor was calculated for each one of the composite specimens separately. It was found that the KI-S.I.F. increases by steps with increasing crack-length.
Crack Propagation in Fibrous Composite Materials Studied by SEM
Authors: Theocaris P.S. , Stassinakis C.A.
Published: March 2007

The modes of crack propagation, as well as the fracture surface of carbon Fiber-Reinforced composites were studied by means of a Scanning Electron Microscope (SEM). The composite specimens used were composed of an epoxy polymer matrix reinforced with unidirectional carbon fibers. In order to study the influence of the difference in the mechanical proper ties of the constituent materials on the overall crack propagation behavior of the composite, three different types of carbon fibers were used, while several amounts of plasticizer were added in the matrix material. From the crack propagation behavior observed from the microphotographs, conclu sions concerning the strength of the composite, the mode of failure, and the adhesion between the phases were derived.
An Exploratory Study Into the Fatigue of Composites Under Spectrum Loading
Authors: Yang J.N. , Du Shanyi
Published: March 2007

A fatigue and residual strength degradation model for constant amplitude cyclic loading has been modified and applied to fatigue of composites under service loading spectra. An exploratory study is made to describe the fatigue behavior of composites subject to spectrum loading using some base-line constant amplitude data. Available test data for both composite laminates and bonded joints under service loading spectra are used to correlate with the theoretical results.
Suspensions of Rodlike Particles: Literature Review and Data Correlations
Authors: Ganani E. , Powell R.L.
Published: March 2007

Recent experimental work on the macroscopic rheological properties of suspensions of rodlike particles in Newtonian and non-Newtonian fluids is reviewed. Correlations are proposed for the shear viscosity-shear rate relationship for semi-concentrated and concentrated suspensions. In the former case, shear thinning behavior is found with the slope of the power law region depending upon fiber aspect ratio. For the concen trated systems, the data are substantially independent of volume fraction and aspect ratio and show slight shear thinning.
Frequency Effects on the Fatigue Life and Damage of Graphite/Epoxy Composites
Authors: Tsai G.C. , Doyle J.F. , Sun C.T.
Published: March 2007

Frequency effects in graphite/epoxy composites are examined in performing fatigue tests at different frequencies and different stress levels. The life data is correlated well by a damage model proposed with only strain as the governing variable. Further, the use of dynamic modulus and creep strain as measures of damage is investigated.
Matrix Cracking in Impacted Glass/Epoxy Plates
Authors: Liu Dahsin , Malvern Lawrence E.
Published: March 2007

In addition to delamination, which has been found to be the major failure mode in a fiber-reinforced laminated composite plate subjected to subperforation impact, matrix cracking and fiber breakage have also been observed. Each failure mode, however, does not generate independently. On the contrary, the different modes interact with one another. Therefore, in order to have an overview of the failure mechanism in an impacted com posite plate, it is necessary to find out the mechanism of every failure mode and the in teractions among them. Microscopic observations of the cross sections of impacted com posite materials have revealed the interaction between matrix cracking and delamination. In this study, however, several techniques have been used to present the matrix cracking patterns in impacted glass/epoxy plates with different thickness, geometries, boundary conditions, stacking sequences, and types of loading. The matrix cracking patterns on the surfaces of impacted plates have been enhanced by dye penetrant while those of the in ternal laminae have been investigated by edge replication. Results have shown that the delamination area on the second interface of a three-lamina glass/epoxy plate coincides with both the central matrix cracking zone of the impacted lamina and the middle crack- free zone of the non-impacted lamina. The matrix cracks in the internal lamina are also restricted by the projected delamination area. The association between delamination and matrix cracking has been discussed and also the effect on matrix cracking of the tensile stresses introduced by the flexural wave.
A Progressive Damage Model for Laminated Composites Containing Stress Concentrations
Authors: Chang Fu-Kuo , Chang Kuo-Yen
Published: March 2007

A progressive damage model is presented for notched laminated composites subjected to tensile loading. The model is capable of assessing damage in laminates with arbitrary ply-orientations and of predicting the ultimate tensile strength of the notched laminates. The model consists of two parts, namely, the stress analysis and the failure analysis. Stresses and strains in laminates were analyzed on the basis of classical lamination theory with the consideration of material nonlinearity. Damage accumulation in laminates was evaluated by proposed failure criteria combined with a proposed property degradation model. A nonlinear finite element program, based on the model, was developed for lami nates containing a circular hole. Numerical results were compared with the experimental data on laminates containing an open circular hole. An excellent agreement was found be tween the analytical prediction and the experimental data.
A Methodology for Accurate Shear Characterization of Unidirectional Composites
Authors: Pindera Marek-Jerzy , Choksi Gaurang , Hidde Jeffrey S. , Herakovich Carl T.
Published: March 2007

A combined experimental-analytical methodology is presented for accurate determina tion of the intralaminar shear modulus G 12 of unidirectional composites using the off-axis tension test and/or the Iosipescu test. It is demonstrated that consistent values of G 12 can be obtained with the two methods provided that: (1) specimen geometry is optimized for the off-axis test, (2) correction factors are employed to account for the shear stress nonuni formity in the test section of Iosipescu specimens. The problem of measuring the shear strength with these specimens is discussed. The 45-deg off-axis tensile coupon is recom mended for determination of the shear modulus. The 0-deg Iosipescu specimen is recom mended for determining an upper lower bound on the shear strength.
Residual Stresses in Carbon Fibre-Thermoplastic Matrix Laminates
Authors: Jeronimidis G. , Parkyn A.T.
Published: March 2007

Residual stresses in composite laminates depend on thermoelastic properties of the material and processing temperatures. Their distribution in the various laminae is a func tion of stacking sequence and ply orientation. In this work residual stresses in APC-2 cross-ply laminates have been investigated. Predictions based on classical laminate theory are compared to measured levels of residual stress obtained from a number of experimen tal techniques. The analysis of the results shows that accurate predictions can be made pro vided that the changes in thermoelastic properties of the materials with temperature are taken into account.
Fracture Mechanics of Unidirectional Composites Using the Shear-Lag Model II: Experiment
Authors: Nairn John A.
Published: March 2007

Fracture experiments were done on double edge notched unidirectional graphite/epoxy composites and the results were analyzed using the shear-lag model approach to fracture mechanics of unidirectional composites described in a companion paper [J. Comp. Mat. , 22:561-588 (1988)]. These composites all failed by longitudinal splitting parallel to the fibers and the entire crack length dependence could be predicted using the fracture mechanics expressions derived in the companion paper and a single material toughness property, the critical longitudinal splitting energy release rate. That energy release rate was found to be 300 J/m2. A new analysis of some similar data by Wright and Ianuzzi [J. Comp. Mat. , 7:430 (1973)] also showed a good fit to the theory in the companion paper. These experimental results verify that the equations derived in the companion paper are the appropriate equations to use for analysis of fracture experiments on unidirectional composites. A standard test procedure for the determination of the fracture toughness of unidirectional composites is proposed.
Modeling of Chemorheology of an Amine-Epoxy System of the Type Used in Advanced Composites
Authors: Mijovic Jovan , Ott Jonathan D.
Published: March 2007

A chemorheological study of an epoxy formulation consisting of tetraglycidyldiamino diphenylmethane (TGDDM) and diaminodiphenylsulfone (DDS) was carried out. An autocatalytic kinetic model with parameters acquired through differential scanning calorimetry (DSC) was obtained. Experimental viscosity data were collected as a function of time and temperature and used to develop two fundamental viscosity models: one based on the branching theory of polycondensation polymers and the other based on the free volume concept using a modified form of the classical WLF equation. The kinetic results were incorporated into the viscosity models and the experimental results checked against the model predictions. The branching theory model provided excellent agreement with both isothermal and non-isothermal viscosity data. The modified WLF model adequately predicted the isothermal viscosity data, but limitations in the model arose in predicting the non-isothermal viscosity.
Closure of the Cubic Tensor Polynomial Failure Surface
Authors: Zhiqing Jiang  , Tennyson R.C.
Published: March 2007

An analytical method has been developed to ensure closure of the cubic form of the ten sor polynomial strength criterion. The intrinsic complexity of the cubic function is such that special conditions must be met to close the failure surface in three-dimensional stress space. These requirements are derived in terms of non-intersecting conditions for asymptotes and an asymptotic plane. To demonstrate the validity of this approach, closed failure surfaces were derived for two graphite/epoxy material systems (3M SP288-T300 and IM7 8551-7). The agreement of test data with this model clearly shows that it is possible to use a higher order cubic failure theory with confidence.
Prediction of Transverse Cracking and Stiffness Reduction in Cross-Ply Laminated Composites
Authors: Lim S.G. , Hong C.S.
Published: March 2007

A modified shear lag analysis, taking into account the concept of in terlaminar shear layer, is employed to predict the onset of a transverse crack and multiple transverse cracking. In this analysis, the boundary conditions are satisfied for any trans verse crack spacing. The crack multiplication is simulated by adjusting the crack spacing. Based on this analysis the laminate stiffness reduction due to the multiple transverse crack ing is also evaluated in cross-ply laminated composites. The energy concept is utilized to assess the effect of 90° layer thickness and the constraining effect of 0° layer on the trans verse cracking behavior of cross-ply laminated composites. Predictions of the onset of a transverse crack and stiffness reduction due to transverse cracks are compared with those of previous analyses and existing experimental data. The present analysis is simple, yet its results show reasonable agreement with experimental results.
Strain-Energy Release Rate Analysis of Plates with Postbuckled Delaminations
Authors: Whitcomb John D. , Shivakumar K.N.
Published: March 2007

Delamination growth due to local buckling of a delamination was studied. Delamination growth was assumed to be related to the total strain-energy release rate, G. In order to calculate the distribution of G along the delamination front, a virtual crack closure technique was developed which is suitable for use with plate analysis. A check of the technique indicated that it is accurate. For square and rectangular delaminations, there is a large variation of G along the delamination front. Hence, self-similar growth is not ex pected. Whether a delamination grows in the load direction or perpendicular to the load direction was found to depend on the current delamination aspect ratio, the strain level, and the absolute size of the delamination.
Symmetric and Asymmetric Dynamic Buckling of Laminated Thin Shells with the Effect of Imperfection and Damping
Authors: Liaw D.G. , Yang T.Y.
Published: March 2007

The emphasis of this paper is to use a thin shell finite element to study the dynamic buckling behavior of a class of thin shell problems due to the effects of three parameters with design significance: (1) axisymmetric and asymmetric imperfections; (2) orthotropic and anisotropic material properties; and (3) Rayleigh viscous damping. Five types of thin shells were considered: (1) an orthotropic annular spherical cap; (2) an ortho tropic, axisymmetrically imperfect, whole spherical shell; (3) an axially compressed, laminated, asymmetrically imperfect, cylindrical shell; (4) an orthotropic, axisym metrically imperfect, spherical cap; and (5) an orthotropic, asymmetrically imperfect, spherical cap. While some basic results are compared with available solutions, extensive new results are also presented. The results quantify the effect of amplitude of imperfec tions, which can significantly reduce the dynamic buckling load. The results also quantify the effects of orthotropic material parameter and viscous damping.
The Application of Double Torsion Testing to Unidirectionally Reinforced Composite Materials
Authors: Frassine R.
Published: March 2007

To characterize the intralaminar fracture behavior of a unidirectional car bon fiber/epoxy resin composite material, two distinct sets of experiments were per formed. First, the tensile mechanical properties of the lamina were determined by testing specimens with different fiber orientation at varying rates of deformation. Then, the Double Torsion technique was applied to characterize the fracture resistance of the material. The strain energy release rate vs. crack speed curve so derived is in agreement with measurements conducted by using the Double Cantilever Beam and Compact Tension techniques. The results of the research indicate that Double Torsion is an attractive tech nique for studying the time-dependent fracture of composite materials.
Extensional and Flexural Waves in a Thin-Walled Graphite/Epoxy Tube*
Authors: Prosser William H. , Dorighi John , Gorman Michael R.
Published: March 2007

Simulated acoustic emission signals were induced in a thin-walled graphite/epoxy tube by means of lead breaks (Hsu-Neilsen source). The tube is of similar material and layup to be used by NASA in fabricating the struts of Space Station Freedom. The resulting waveforms were detected by broad band ultrasonic transducers and digitized. Measurements of the velocities of the extensional and flexural modes were made for prop agation directions along the tube axis (0 degrees), around the tube circumference (90 degrees) and at an angle of 45 degrees. These velocities were found to be in agreement with classical plate theory.
Effects of Seawater Immersion on the Impact Resistance of Glass Fiber Reinforced Epoxy Composites
Authors: Strait Larry H. , Karasek Mark L. , Amateau Maurice F.
Published: March 2007

Little, if any, information regarding the effects of seawater immersion on the impact resistance of composite materials has been published to date. In the present study, instrumented impact tests were used to characterize such effects for two glass fiber reinforced epoxy composites. One material consisted of continuous nonwoven E-glass fibers in a conventional epoxy resin and the other consisted of woven E-glass fibers in a rubber toughened epoxy resin formulated specifically for marine applications. In the conventional epoxy system, the energy for incipient damage increased significantly follow ing seawater immersion due to plasticization of the matrix by the absorbed moisture. Both glass/epoxy systems experienced substantial reductions in peak load and energy absorbed at peak load as a result of moisture-induced degradation of the fibers and fiber/matrix interface. Energy after peak load decreased in the conventional epoxy system follow ing immersion. Total energy absorbed was reduced significantly for both glass/epoxy systems following seawater immersion. These results indicate that moisture-induced degradation can significantly reduce the impact resistance of glass fiber reinforced epoxy composites.
Effect of Fiber Orientation and Sample Geometry on the Effective Thermal Conductivity of a Uniaxial Carbon Fiber-Reinforced Glass Matrix Composite
Authors: Hasselman D.P.H. , Bhatt H. , Donaldson K.Y. , Thomas J.R.
Published: March 2007

From solutions for the thermal conductivity of anisotropic solids, it is pre dicted that the effect of fiber angle on the thermal conductivity of uniaxial fiber-reinforced composites is a function of sample geometry. Experimental data for the effect of fiber an gle on the thermal conductivity of a uniaxial carbon fiber-reinforced aluminoborosilicate glass matrix composite taken from three different sample geometries are presented in sup port of this conclusion. The thermal conductivity of the center portion of samples with a thickness in the direction of heat flow much smaller than their width agreed very well with the corresponding effect predicted for a composite plate of infinite extent. Similar results were obtained for "angled" samples, with a geometry such that the net direction of heat flow was parallel to the fiber direction. In contrast, for samples of rectangular geometry with a thickness of the order of the width, the thermal conductivity data for fiber angles greater than about 45° agreed very well with those predicted for a narrow composite strip with thermally insulated sides. At lower fiber angles, the data for these latter samples were intermediate to those predicted for the infinite composite plate and the insulated strip. The results of this study imply that care needs to be taken in the selection of specimen geom etry when measuring the effect of fiber orientation on thermal conductivity of uniaxial composites, and when using such data in the thermal analysis of composites with different shape and boundary conditions.
The Use of Strain Energy-Based Finite Element Techniques in the Analysis of Various Aspects of Damping of Composite Materials and Structures
Authors: Hwang S. Jimmy , Gibson Ronald F.
Published: March 2007

This paper presents a review of the authors' recent work on the use of a strain energy-based finite element approach to the analysis of various aspects of damping of composite materials and structures. Particular interest was paid to the design and analy sis flexibility offered by finite element implementation of the strain energy method, and both micromechanical and macromechanical models are presented for the analysis of damping in composites. Previous work using micromechanical models to study the effects of fiber interaction, fiber aspect ratio, and fiber/matrix interphase size on the composite damping are described. Various macromechanical models for study of the effects of in terlaminar stresses, fiber orientation, vibration coupling, and constrained layer damping treatments in composites are discussed. Some experimental results from previous work are compared with analytical results from the strain energy-based finite element models. Finally, recommendations on ways of improving and optimizing damping in composites are offered. This review should be of interest to designers who must deal with vibration control and damping of composite materials and structures.
Matrix Cracking and Delamination in Laminated Composite Beams Subjected to a Transverse Concentrated Line Load
Authors: Sheng Liu  , Kutlu Zafer , Chang Fu-Kuo
Published: March 2007

An investigation was performed to study the damage mechanism and mechanics of flat and cylindrical laminated composite beams subjected to transverse con centrated loading. The major focus of the study was to fundamentally understand the inter action between matrix cracking and delamination propagation in composite structures resulting from transverse loadings. An analytical model was developed which consists of a stress analysis for calculating stresses and strains in the composites, a contact analysis for handling the interface condition of cracked surfaces during loading, and a failure anal ysis for predicting matrix cracking and delamination growth. Experiments were also per formed to verify the model and the numerical calculations. Overall, the results of the calculations based on the analysis compared favorably with the existing data and the data generated during the investigation.
Fatigue Failure of Composite Bolted Joints
Authors: Herrington P.D. , Sabbaghian M.
Published: March 2007

The effects of a number of parameters on the fatigue characteristics of a bolted graphite/epoxy composite laminate are investigated. In particular, tests were per formed in order to study the influence of three independent parameters; applied stress level, orientation of the outer layer reinforcing filaments, and the bolt torque level on the fatigue life of a graphite/epoxy composite. Analysis of variance and censoring techniques were used to analyze the experimentally obtained data. Fatigue life data was determined to be adequately characterized by using a log-normal distribution.
Micromechanical Modeling of Composite Compressive Strength
Authors: Yong Li Xu  , Reifsnider Kenneth L.
Published: March 2007

Composite compressive failure is studied using a micromechanical (beam-on-elastic foundation) model, and the stiffness of the foundation is determined through an elasticity solution of the foundation model problem. An explicit expression has been derived for evaluation of composite longitudinal compressive strengths (CLCS). It is found that this expression predicts relatively lower CLCS compared to classical models, and closely matches some experimental data for carbon fiber/epoxy composites. It is found that a complete matrix slippage will reduce the CLCS by over 50%.
Adolescent Divergent Thinking
Authors: Jaquish Gail A. , Ripple Richard E.
Published: March 2007

A cross-cultural replication study was conducted to assess divergent thinking in preadolescents and adolescents. Participants (N = 119) were Cantonese-speaking Chinese residents of Hong Kong, recruited through primary and secondary schools. Participants responded in writing to a divergent thinking assessor based on auditory stimuli. Scores were obtained for fluency, flexibility, and originality of thought. Adolescents scored significantly higher than preadolescents on all three divergent thinking measures. A MANOVA test indicated an overall absence of main effects for sex and sex-by-age-group interactions. Results are discussed in comparison to a similar study previously conducted with American adolescents.
The Influence of Television on Measured Cognitive Abilities
Authors: Lonner Walter J. , Thorndike Robert M. , Forbes Norma E. , Ashworth Clark
Published: March 2007

In 1979 and again in 1982 data were collected in rural Alaska to assess certain effects of commercial entertainment television, which began in 1977 in selected rural sites. The findings reported here include two major culture groups: the northern Inupiat Eskimo (four villages) and the southwestern Tlingit and Haida (two villages). In 1979, half of the villages had received television for two years; by 1982 all villages had reception capabilities, allowing for a longitudinal as well as cross-sectional study of the differential effects of television on children. Age, sex, culture area, and amount of television watched were major predictor variables while scores on four cognitive tests (CEFT, Kohs Blocks, Raven Matrices, and PPVT) were the criterion variables. Data analysis was a three-stage procedure in which the independent variables were treated as sets. There was no evidence that television by itself had a major effect on cognitive abilities. Numerous interactions show that television in Alaska did not, during the period of the study, have a uniform effect on the children in the study. The social learning concept of reciprocal determinism can be used to explain the complex ways in which television interacts with person variables and other environmental variables to influence test scores.
Family Environment, Educational Aspirations, and Academic Achievement in Two Cultural Settings
Authors: Seginer Rachel , Vermulst Ad
Published: March 2007

This study tested a four-step model consisting of family background, perceived parental support and demandingness, educational aspirations, and academic achievement. The model was estimated on data collected from eighth graders ( N = 686) growing up in two cultural settings: transition to modernity (Israeli Arabs) and Western (Israeli Jews). LISREL analyses performed separately for the four ethnicity-by-gender groups showed good fit of the model and supported the predicted differences in the links between the latent variables across ethnicity and gender. Specifically, family background had direct and indirect effects on the academic achievement of Arab but not Jewish adolescents. The indirect family background-academic achievement path showed gender differences only for the Arab adolescents via educational aspirations for girls and parental demandingness for boys, and parental demandingness was directly related to academic achievement of Arab boys and Jewish adolescents. Discussion explained ethnic and gender differences in terms of demographic and sociocultural conditions.
Toward a Model of Terrorist Behavior in Hostage-Taking Incidents
Authors: Wilson Margaret A.
Published: March 2007

Behavior in terrorist hostage taking is examined using published accounts of 100 incidents of aerial hijack and 60 incidents of barricade siege occurring worldwide over the past three decades. The use of multi-dimensional scalogram analysis demonstrates that behavior in terrorist hostage taking is highly structured. Behavioral similarities between incidents carried out by the same terrorist organization are demonstrated, and the structures underlying the use of resources in barricade siege and the demands issued in aerial hijacking are presented. The implications for theory development and training and decision making in hostage negotiation are discussed.