bluuebunny/crossref_metadata_2025 huggingface dataset:
Adding Values
Authors: Gunter Helen
Published: October 2003

This article reports on research into the work of LEA appraisal co-ordinators in the implementation of teacher appraisal based on the 1991 Regulations. Appraisal co-ordinators in 10 LEAs in the north of England were interviewed with a specific focus on how and why the 1991 Regulations were interpreted and translated into locally based schemes. It is argued that the agency ofthe appraisal coordinators in the form of their professional educational values and their location within a complex network of stakeholder interests enabled the creation of appraisal schemeswhich have an overtly developmental purpose. Appraisal could very easily have been technicist and minimalist, and teacher experience of developmental systems is directly related to the values added by those discharged with the responsibility of implementation. This values-added process is difficult to measure, and this article seeks to enable glimpses of it through an analysis of the words of LEA appraisal co-ordinators.Holding on to professional educational values is proving difficult as the drive towards the efficiently managed state closes down the opportunities for dialogue and the articulation of professionally committed beliefs.
Female Administrators and School-Based Management
Authors: Limerick Brigid , Anderson Cheryl
Published: October 2003

This paper reports upon the perceptions of 23 senior women in Education Queensland on the impact of School-Based Management (SBM) on their ways of leading and on their career opportunities. The women interviewed were all graduates of a Women in Management course run by the Queensland University of Technology. Those women working in primary schools and in secondary schools trialling SBM felt that SBM would legitimize the way they led their schools and provide them with further opportunities to challenge the accepted discourse of educational administration. The women working in secondary schools were sceptical about its introduction. However, almost all the women felt that it would not enhance their future career prospects as the culture and make-up of the central bureaucracy remains masculinized.
Parents’ Representatives in the New Participatory School Council in Belgium (Flanders)
Authors: Verhoeven Jef C. , Van Heddegem Ilse
Published: October 2003

Parents were, until the establishment of the Participation Council (1991) and the Local School Council (1988), not used to participating in school policy making. The establishment of these new participatory councils was an important innovation. The purpose of this paper is to report upon the opinions of parents concerning both councils. In order to examine these, the authors employed a survey based approach. The data suggests that, whatever their other merits, these new bodies are not on their own a sufficient condition for enabling increased levels of parental participation in the decision-making processes of schools. If this is to happen, councils will need to develop a new culture of cooperation. Only then will parents have a real say in school policy making.
Changing Leaders’ Educational Hearts
Authors: McCrea Nadine , Ehrich Lisa
Published: October 2003

This article was written as a statement of position regarding educational leadership. It is a research and refinement of a framework that can happen via a heart metaphor. It takes a proactive stance, blending the tasks of managing education with the human encounters of educators during their day-to-day teaching and learning. It is proposed that leading and leadership are at the heart of managing all types of education from early childhood settings to high schools to universities. This proposition varies from an established business management approach by creating a leadership framework centred with a feminine, but not necessarily feminist, heart with four chambers and multiple heartbeats. It proclaims that leading ought to be the educational lifeblood that guides and flows into planning, organizing and monitoring teachers’ work. This is a heartfelt message for change that may seem light-hearted to some readers.
Immobilization of α-[di-(β-Chloroethyl)-Amide]-N-(m-Nitrobenzoyl)-D,L-Asparagic Acid on Xanthan
Authors: Marcel Popa , Lăcrămioara Bălăită Rusu , Valeriu Şunel
Published: October 2003

The paper studies the coupling reaction, through ester-type covalent bonds, of an oxazolone derived from the N-(m-nitrobenzoyl)-L-asparagic acid, the cycle of which is opened with an N-mustard derivative, on xanthan (a polysaccharide of microbian synthesis), in conditions of activation with dicyclohexyl carbodiimide.

The coupling product has been characterized through elemental analysis and IR spectroscopy.

For the establishment of the capacity of the active principle's controlled release by the polymer-active principle system thus obtained, active principle's release kinetics from the polysaccharide support, in conditions of basic hydrolysis, is studied.

In vivo tests realized on mice proved the antitumoral activity of the compounds resulted by chemical bonding of the N-mustard derivative on xanthan.
Spinal Fixation Device: A 6-Year Postimplantation Study
Authors: Mohanty Mira , Baby Sulekha , Menon K. V.
Published: October 2003

Long-term tissue response to a metal device is described here. The components of a spinal fixation device were removed 6 years after implantation, following the need for revision surgery after a fall. Scanning electron microscopy (SEM) revealed changes in surface topography of the metal. Examination of the adjacent tissue showed a chronic inflammatory response with occasional metal debris. Immunohistochemistry identified the predominant macrophages and abundant neovascularization. The presence of macrophages in tissues adjacent to the implants, in an otherwise asymptomatic person, is noteworthy.
Reduced Platelet Adhesion on the Surface of Polyurethane Bearing Structure of Sulfobetaine
Authors: Yuan J. , Zhang J. , Zhu J. , Shen J. , Lin S. C. , Zhu W. , Fang J. L.
Published: October 2003

Poly(etherurethane)s are widely used as blood-contacting biomaterials due to their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for the more demanding applications. Surface modification is an effective way to improve the blood compatibility and retain the bulk properties of biomaterials. The purpose of present study was to design and synthesize a novel nonthrombogenic biomaterial by modifying the surface of poly(etherurethane) with zwitterionic monomer. Films of polyurethane were grafted with sulfobetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 C in the presence of di-n-butyl tin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IR spectra; a maximum number of free NCO group was obtained after a reaction time of 90 min. In the second step, the hydroxyl group of 4-dimethylamino-1-butanol (DMAB) was allowed to react in toluene with isocyanate groups bound on the surface. In the third step, sulfobetaine was formed on the surface through the ring-opening reaction between tertiary amine of DMAB and 1,3- propanesultone (PS). It was characterized by ATR-IR, XPS. The data showed that the grafted surfaces were composed of sulfobetaine. The results of the contact angle measurements showed that they were strongly hydrophilic. The state of platelet adhesion and shape variation for the attached platelets was described. The modified surface shows excellent blood compatibility feature by the low platelet adhesion.
Hybridoma Cells Immobilized on Nonwoven Polyester Fabric Discs: Proliferation and Monoclonal Antibody Production in Stationary Culture
Authors: Aslankaraoğlu Esin , Gümüşderelioğlu MenemŞE , Gürhan S. İsmet
Published: October 2003

Mouse hybridoma cells (O146S) producing a monoclonal antibody against the 146S antigenic particles of O type apthhoviruses were proliferated on the nonwoven polyester fabric (NWPF) discs in a stationary culture. A series of batch experiments were performed in Petri dishes containing RPMI 1640 medium supplemented with 10% (v/v) fetal bovine serum. During the cultivation period glucose and lactate concentrations were measured and monoclonal antibody concentration was determined by sandwich enzyme-linked immunosorbent assay (ELISA). The results showed that in the presence of the NWPF discs cell viability, cell yield, and total monoclonal antibody production was higher than that of the disc-free culture.
Housing Vouchers and Residential Mobility
Authors: Varady David P. , Walker Carole C.
Published: October 2003

Existing research suggests that tenant-based subsidies (housing vouchers) can help to deconcentrate poverty and improve the quality of life of low-income families. The Gautreaux Assisted Housing Program and the Moving to Opportunity (MTO) demonstration program have been shown to help families move to safer neighborhoods and ones with better public schools. The regular Section 8 program has been successful in facilitating moves to low-poverty areas in places like Alameda County, California, but public housing families have had difficulties in Chicago. Research on mixed-income communities has provided little evidence that social mixing has any direct positive impacts through social interaction and/or social networks. However, the lack of research on the long-term impacts on children, such as future improvements in their employment circumstances due to better educational attainment, makes it impossible to offer conclusive assessments on the connection between income mixing and social mobility.
Agencies of Globalization and Third World Urban Form: A Review
Authors: Pizarro Rafael E. , Wei Liang , Banerjee Tridib
Published: October 2003

This article proposes a theoretical framework to examine the effects of globalization on urban form and urbanism in the third world. Toward developing such a framework, the authors conceptualize globalization as the removal of political and physical barriers for the free movement of capital, people, information, and culture among nations and propose that the removal of such barriers have consequences on the cities of the third world. These consequences, the authors suggest, are expressed in the configuration of urban space, urban form, and urbanism in the third world. The authors look at those four agencies of globalization (movement of capital, people, information, and culture) and their effects. The goal of the article is to offer a critical framework for reviewing contemporary literature on globalization and third world urban form.
Effectiveness of Maleated and Acrylic Acid-Functionalized Polyolefin Coupling Agents for HDPE-Wood-Flour Composites
Authors: Li Qingxiu , Matuana Laurent M.
Published: October 2003

The performance of fiber reinforced thermoplastic composites strongly depends on solid fiber-matrix adhesion to allow stress transfer between the phases. Fiber surface modification with coupling agents is generally needed to induce bond formation between the fiber and the polymer. This study investigated the effects of coupling agent's functional monomer (acrylic acid vs. maleic anhydride) and base resin (polyethylene (PE) vs. polypropylene (PP)) types on the tensile and flexural properties of high-density polyethylene (HDPE)-wood-flour composites. The interfacial adhesion between wood flour and HDPE matrix was examined using environmental scanning electron microscope. The experimental results indicate that the types of functional monomer and base resin are important factors determining the effectiveness of functionalized coupling agents for HDPE-wood-flour composites. Maleic anhydride-functionalized polyolefins perform better than acrylic acid counterparts whereas PE-based maleated coupling agents are more effective than PP-based counterparts in improving the strength properties of HDPE-wood-flour composites.
Thermal Residual Stress Simulation in Thermoplastic Filament Winding Process
Authors: Schlottermuller Martin , Lu Haibo , Roth York , Himmel Norbert , Schledjewski Ralf , Mitschang Peter
Published: October 2003

The present paper describes an advanced model to simulate the residual stresses of reinforced filament wound thermoplastic composites. The nonlinear characteristics of the problem are reduced by decoupling some of the phenomena and the associated dependent variables into submodels. Four submodels are used here: fiber motion, thermal, kinetic and rheological as well as a stress-strain submodel. The models were tested on a selected GF/PP sample chosen from a sensitivity study which is presented also. The effect of individual process parameters on the residual stresses in filament wound parts is rated by a sensitivity study.
Interface Behavior in Polypropylene Composites
Authors: Mukhopadhyay S. , Deopura B. L. , Alagiruswamy R.
Published: October 2003

Thermoplastic composites have been put to lot of use due to some of their inherent advantages. Amongst them, experiments on Polypropylene (PP) have taken a major share. Fiber-matrix interface in composites influences many bulk mechanical properties. Reliable control of the degree of adhesion between fiber and matrix is required if a composite is to be used as a structural material. This article reviews the importance of the different parameters affecting the properties of the interface with PP as the matrix with a special focus on transcrystallinity.
Design and Experimental Validation of an Adaptive Neurocontroller for Vibration Suppression
Authors: Jha Ratneshwar , He Chengli
Published: October 2003

The real time sensing and actuation capabilities of smart structures are employed for active vibration control. A neural network based adaptive controller is designed and validated experimentally for nonlinear vibration suppression. Piezoelectric actuators are used to reduce the vibrations of a cantilevered plate subject to impulse, sine wave, and band-limited white noise disturbances. A multilayer perceptron with a single hidden layer of neurons is used as the controller. For an adaptive control system, the neurocontroller learns online in real time starting with random weights and biases. For fast learning, the Levernberg-Marquardt backpropagation algorithm is implemented by writing a C-file S-function used with MATLAB/Simulink. The learning rate is varied during the minimization of the cost function. Experimental results demonstrate quick learning, excellent closed-loop performance, and robustness of the adaptive neurocontroller.
Closed-Loop Position Control of Preisach Hystereses
Authors: Gorbet R. B. , Morris K. A.
Published: October 2003

We discuss closed-loop control of hysteretic systems having Preisach representations. We apply dissipativity methods, the key component of which is the determination of an appropriate supply rate. The concept of cyclo-dissipation is used to identify a new supply rate for Preisach hystereses and dissipativity with respect to this supply rate is shown. The result is useful in the design of output feedback controllers, and complements a previous result using feedback of the output derivative. We consider the specific example of a shape memory alloy actuator and identify a class of controllers which provide stability of position feedback with current as the control variable. This demonstrates one way in which system dynamics that couple with hysteresis can be included in controller design.
Experimental Investigation of Damage Detection in Composite Material Structures Using a Laser Vibrometer and Piezoelectric Actuators
Authors: Ghoshal A. , Chattopadhyay A. , Schulz M. J. , Thornburgh R. , Waldron K.
Published: October 2003

An experimental investigation to detect embedded delamination and other forms of damage in heterogeneous structures using smart materials and a laser vibrometer is presented. Typically, piezoelectric actuators and sensors have been used for characterizing the presence of damage in composite structures. However, the interpretation of vibration responses in identifying damage using such a procedure is strongly dependent upon the numbers and types of sensors and actuators used. The use of Vibration Deflection Shapes (VDSs), which are the actual vibration patterns of a structure undergoing steady-state vibration, is an alternative approach that is investigated in this paper. Experiments are conducted on composite structures with piezoelectric actuator patches and embedded delaminations, using the VDS method and a Scanning Laser Doppler Vibrometer. The laser vibrometer provides a dense pattern of measurements of the structural response, which effectively increases sensor density compared to the widely spaced piezoceramic sensors used in other techniques. A series of experiments is performed on composite plate-beams with various sizes, ply-level locations, and placement of delaminations to comprehensively evaluate the performance of the laser technique. The VDSs are shown to be sensitive to structural parameter variations, and hence can be used to detect and locate damage in large composite structures, including a woven fiberglass curved plate and a honeycomb intertank panel. The successful experimental demonstration of the procedure using different test articles shows that the VDS method can become an effective and time saving tool for structural health monitoring, particularly for detection of damage in composites.
Shape Memory Mechanics of an Elastic Memory Composite Resin
Authors: Abrahamson Erik R. , Lake Mark S. , Munshi Naseem A. , Gall Ken
Published: October 2003

Substantially more attention has been given in the past to shape memory alloys and shape memory ceramics than to shape memory polymers because unreinforced shape memory polymers have much lower stiffness and recovery force potential than shape memory alloys and shape memory ceramics. However, when incorporated into a fiber-reinforced composite, both the stiffness and the recovery force of a shape memory polymer can be dramatically improved. This paper presents recent advances in characterizing the shape memory mechanics of a thermoset shape memory polymer resin for Elastic Memory Composite (EMC) materials. In particular, heretofore undocumented response behavior is characterized through a series of thermo-mechanical tests of a commercially available EMC resin, and a lumped parameter model is adapted to accurately correlate this behavior. Through application of this model, it appears that the molecular transition associated with the shape memory effect occurs at a temperature other than the glass transition temperature of the resin.
Modeling of a Magnetorheological Actuator Including Magnetic Hysteresis
Authors: An Jinung , Kwon Dong-Soo
Published: October 2003

Magnetorheological (MR) actuators provide controlled torque through control of an applied magnetic field. Therefore knowledge of the relationship between the applied current and output torque is required. This paper presents a new nonlinear modeling of MR actuators considering magnetic hysteresis to determine the torque-current nonlinear relationship. Equations for transmitted torque are derived according to mechanical shear configurations of the MR actuator. Hodgdon's hysteresis model is used to capture the characteristics of hysteresis nonlinearity in the MR actuators. An MR actuator test setup has been constructed using a commercial MR brake to evaluate the proposed model. The measured torque shows hysteresis effects as the current increases and decreases. Using Hodgdon's hysteresis model of the magnetic circuit and Bingham model of the MR fluid, a novel nonlinear model of the MR actuator is obtained as a torque estimator for practical torque control purpose. The validity of the theoretical results is verified by comparison between experiments and simulations. Furthermore, the current versus torque frequency response of the MR actuator is examined to evaluate its applicability to torque control. The bandwidth of the MR actuator is high enough for especially haptic applications.
Damping Effects on the State-Switched Absorber Used for Vibration Suppression
Authors: Holdhusen Mark Horner , Cunefare Kenneth A.
Published: October 2003

A state-switched device is conceptually capable of instantaneously changing its mass, stiffness, or damping. Such a device will exhibit different dynamical response properties (modes and resonance frequencies) depending on its current state. A state-switched vibration absorber exploits the state-switching concept for the purposes of enhanced vibration suppression. Between each state switch, it is fundamentally a passive vibration absorber, but one which exhibits a different tuning frequency for each possible state. A state-switched vibration absorber therefore has a greater effective bandwidth than a classical passive absorber. This paper considers the role of damping in the state-switching concept for a simple one-degree of freedom system and for a two-degree of freedom system. Certain values of damping in the system improve performance, while other values hinder the performance of the state-switched absorber, as compared to classical absorbers. The predicted performance of the system also depends upon the particular damping model used, such as viscous absorber or system modal damping. Damping values also affect the frequency of switch events that occur during the response of the system. In general, the highest relative performance of the state-switched absorber as compared to a classical vibration absorber occurs at low values of damping.
Design and Experimental Verification of Pseudoelastic-Based Constant-Force Springs
Authors: Soroushian Parviz , Chowdhury Habibur , Nossoni Ali
Published: October 2003

Constant-force springs were designed with Ni-Ti pseudoelastic alloy. Through local concentration of flexural deformations, the design produces “pseodoelastic hinges” under relatively small deformations. Constant moments at these “pseudoelastic hinges” produce a relatively constant level of spring force under increasing deformations. Local concentration of flexural deformations are achieved in this design through bracing the spring element outside the locations where deformations concentrate. Experimental data verified the desirable constant-force behavior of the springs and their desirable fatigue life, relaxation attributes, and corrosion resistance. The pseudoelastic spring design presented here is subject of approved and pending U.S. patent applications.
Optimal Sizes and Placements of Piezoelectric Actuators and Sensors for an Inflated Torus
Authors: Jha Akhilesh K. , Inman Daniel J.
Published: October 2003

One of the limitations of a piezoelectric actuator is the amount of force it can exert. Hence, it is important to optimize the locations and sizes of the actuators so that the required control effort is minimal. Similarly, to obtain good signal-to-noise ratio, sensors should be chosen to provide maximum output for the vibration in the modes of interests. These problems become more critical as the number of actuators and sensors increases, and the mode shapes become more complicated. This is true for the case of an inflated torus. In this study, we try to find optimum places and sizes of actuators and sensors attached to an inflated toroidal shell using a genetic algorithm. Using the expressions for the generalized forces and sensor voltages, modal forces and modal sensing constants are determined. To obtain a cumulative performance measure for all the controlled and observed modes, controllability and observability indices are used. Using these performance indices, optimal locations and sizes of the actuators and sensors are determined so that the actuators and sensors provide good control and sensing authorities in the considered modes. Finally, vibration suppression of the inflated torus using these actuators and sensors has been demonstrated using an optimal control technique.
Dynamic Behavior of Telescopic Actuators
Authors: Vendlinski James , Brei Diann
Published: October 2003

While piezoelectric actuators are very useful for high frequency applications, their small strokes pose a significant constraint to most applications. Internally leveraged amplification schemes overcome this constraint, but at the cost of output force and bandwidth. The telescopic actuation architecture employs a novel internal amplification scheme that provides a moderate stroke amplification (up to 20 times) while maintaining high force and bandwidth. This paper presents a study of the dynamic behavior of this generic type of actuation. Because of the complexity of the structure, a new modeling technique based upon adaptation of the transfer matrix method was developed. As validation, a three cylindrical PZT5H telescopic actuator was fabricated and experimentally tested.
Thermo-Electro-Mechanical Behavior of Ferroelectric Materials Part II: Introduction of Rate and Self-Heating Effects
Authors: Weiland Lisa Mauck , Lynch Christopher S.
Published: October 2003

A micro-electro-mechanical model of the behavior of piezoelectric ceramics including thermal, rate, and self-heating effects is presented and simulations are compared to experimental data. The rate dependent model is an extension of an earlier rate independent model. Results include analytical and numerical investigations of the behavior of piezoelectric ceramics. The model is based on physical mechanisms and includes elastic, dielectric, and piezoelectric anisotropy. Moreover, the model is based on an internal energy approach so that work-energy relations may be directly applied. Special consideration of potential physical mechanisms responsible for material behavior in the largely unexplored intermediate rate regime (50-1000 Hz) at high fields is given. Results from the model give insight into material behavior.
Thermo-Electro-Mechanical Behavior of Ferroelectric Materials Part I: A Computational Micromechanical Model Versus Experimental Results
Authors: Mauck Lisa D. , Lynch Christopher S.
Published: October 2003

A micro-electro-mechanical model of the behavior of piezoelectric ceramics including thermal effects is presented and compared to experimental data. Results include analytical and numerical investigations of the behavior of piezoelectric ceramics. The model is based on physical mechanisms and includes elastic, dielectric, and piezoelectric anisotropy. Moreover, the model is based on an internal energy approach so that work-energy relations may be directly applied. Results from the model give insight into material behavior.
Combined Finite Element Analysis - Genetic Algorithm Method for the Design of Ultrasonic Motors
Authors: Bouchilloux Philippe , Uchino Kenji
Published: October 2003

The operation of a linear or rotary ultrasonic motor relies on the production of an elliptical vibration at the surface of the stator. To achieve a suitable vibration state, many ultrasonic motors use a combination of structural modes of the stator. Because these modes may be different in nature, designing a viable stator is not trivial. In addition, the design may be complicated by other considerations, such as the electromechanical coupling coefficient of the piezoelectric elements, the amplitude of the vibrations, and the force factor of the device. Similarly, it may also be desired to incorporate parameters such as the operation frequency, geometrical dimensions and weight, electrical current and so on, which may render the design problem extremely difficult to solve.

To help in designing such ultrasonic structures, it is proposed to use the genetic optimization method in combination with the finite element method. The combination of these two design tools is innovative and provides a unique approach to the complex problem of ultrasonic motor design. In this paper, the general aspects of the method utilized are reviewed and an application example that includes experimental verification data is provided.
Information Acquisition Bias during the Preparation of Group Discussion
Authors: van Hiel Alain , Franssen Vicky
Published: October 2003

The present research investigates whether prospective minority and majority members exhibit information acquisition bias to exert social influence in a forthcoming group interaction. In particular, the question of whether (a) the mere fact of attending to a forthcoming group discussion and (b) group decision rule (majority rule vs. unanimity rule) alter the orientation toward supporting evidence is investigated. This study found that minorities exhibit greater information acquisition bias than equal and majority factions, especially when the minorities expected a group interaction. Group decision rule did not have any significant effect. The absence of effects of group decision rule and the relationship between coalition formation and cognitive processes are discussed.
Further Understanding of Trust and Performance in Virtual Teams
Authors: Aubert Benoit A. , Kelsey Barbara L.
Published: October 2003

Trust has been deemed to be critical in ensuring the efficient operation of virtual teams and organizations. This study empirically verifies ability and integrity as being antecedents of trust formation in virtual teams. However, effective team performance was found to be independent of the formation of trust. Further analysis suggests that information symmetry and good communication distinguish high performance teams from low performance teams.
Quality of Team Service
Authors: Gibson Cristina B.
Published: October 2003

Consistent with cognitive cross-cultural frameworks, cultural tendencies toward field independence, corresponding team quality orientations, quality improvement focus, and patients’ratings of service quality were examined for 71 U.S. and Indonesian nursing teams, using both qualitative and quantitative methods. Results provide partial support for the hypotheses, demonstrating preliminary evidence that (a) field independence is associated with quality orientation in complex ways, and (b) quality orientations mediate the relationship between quality improvement focus and quality. These findings are discussed in terms of psychological theory, research methods, and managerial implications.
High Strain Rate Thermo-Inelasticity of Damaged AISI 316H
Authors: Micunovic M. , Albertini C. , Montagnani M.
Published: October 2003

Two groups of AISI 316 H specimens, previously subjected either to creep or low cycle fatigue, are examined by tension at 550 C in the strain-rate range 1/210 3,103 s1. The specimens previously treated by creep suffered various levels of creep strains while the specimens predamaged by LCF had various LCF strain critical cycle numbers (as a measure of initial life time). A third group of virgin specimens was tested in the same strain rate range but at diverse room temperatures from 20 to 550 C. First dissipation function is determined and then some memory type unified evolution equations are analyzed and calibrated for as-received, creep-damaged and LCF-damaged specimens, covering stress, strain, strain rate and temperature relations and accounting for strain and strain-rate hardening. The material constants entering the equations are damage-dependent. Comparisons with some empirical and microstructural models are made. Our analysis based on modeling and experimental data is compared with Lemaitre's strain equivalence principle. Standard damage mechanics models are then matched with effective field homogenization method.
A Plastic-Damage Model for Stress-Strain Behavior of Soils
Authors: Al-Shayea N. A. , Mohib K. R. , Baluch M. H.
Published: October 2003

This paper presents a constitutive model for soil, which combines elements of plasticity with damage mechanics to simulate the stress-strain behavior. The model is primarily suitable for soil types that exhibit a postpeak strain-softening behavior, such as dense sand and stiff clay. The postpeak stress drop is captured by the elasto-damage formulation, while the plasticity is superimposed beyond the elastic range. The total strain increment is composed of an elasto-damage strain increment and a plastic strain increment. The elasto-damage strain increment is found using the elasto-damage formulation, while the plastic strain increment is found using either the Drucker-Prager classical plasticity model or as a function of damage strain.

To implement this model, an experimental program was conducted on local cohesive and cohesionless soils. Various physical and mechanical properties of these soils were determined. Both triaxial tests and hydrostatic tests were performed under different confining pressures, in order to obtain the model parameters. These parameters were used to calibrate the model, which was coded in computer programs to simulate the stress-strain behavior of soils. The model was verified and found to be a good predictor of the geomaterial response for the selected stress path.
Combined Model of Strain-Induced Phase Transformation and Orthotropic Damage in Ductile Materials at Cryogenic Temperatures
Authors: Garion Cedric , Skoczen Blazej
Published: October 2003

Ductile materials (like stainless steel or copper) show at cryogenic temperatures three principal phenomena: serrated yielding (discontinuous in terms of dσ/dε), plastic strain-induced phase transformations and evolution of ductile damage. The present paper deals exclusively with the two latter cases. Thus, it is assumed that the plastic flow is perfectly smooth.

Both in the case of damage evolution and for the 0 phase transformation, the principal mechanism is related to the formation of plastic strain fields. In the constitutive modeling of both phenomena, a crucial role is played by the accumulated plastic strain, expressed by the Odqvist parameter p. Following the general trends, both in the literature concerning the phase transformation and the ductile damage, it is assumed that the rate of transformation and the rate of damage are proportional to the accumulated plastic strain rate. The 0 phase transformation converts the initially homogenous material to a two-phase heterogeneous ”composite”. The kinetics of phase transformation is described by the relevant linearized law of evolution of the volume fraction of 0 martensite in the austenitic matrix [Garion, C. and Skoczen, B. (2002a). The evolution of orthotropic damage is characterized by the fact that the principal directions of damage are generally not colinear with the principal directions of stress. The damage rate tensor depends linearly on the strain energy density release rate tensor (conjugate force) and on the material properties tensor C, that reflects the orthotropy level. The relevant kinetic law of damage evolution and the combined constitutive model, including phase transformation, are developed in the present paper. The model is particularly suitable to describe the evolution of highly localized damage fields in thin-walled shells, subjected at cryogenic temperatures to the loads far beyond the yield point. It has been applied to the prediction of the response of the bellows expansion joints (corrugated thin-walled shells) designed for the inter-connections of the Large Hadron Collider at CERN.
Damage Mechanisms in Nanolayered Metallic Composites
Authors: Misra A. , Kung H. , Hammon D. , Hoagland R. G. , Nastasi M.
Published: October 2003

The strengths of metallic multilayers, composed of alternating layers of soft metals such as Cu and Nb, approach the theoretical limit of material strength when the bilayer periods are on the order of a few nanometers. We have investigated the damage mechanisms in these ultra-high strength nanolayered composite materials subjected to monotonic deformation. Large strain plastic deformation such as room temperature rolling does not lead to any dislocation cell structure formation within the layers indicating that the deformation and dislocation storage mechanisms in nanostructured materials are completely different from the bulk. In bulk metals, dislocation pile-ups lead to heterogeneous slip, but in nano-materials, deformation by single dislocations on closely spaced glide planes results in more homogeneously distributed slip. The implications of the high tensile strengths and homogeneous slip on the fatigue properties of nanolayered materials are also discussed.
Evaluating Micromechanical Properties at Surfaces Using Nanoindentation with Finite-Element Modeling
Authors: Knapp J. A. , Follstaedt D. M. , Myers S. M.
Published: October 2003

Detailed finite-element modeling of nanoindentation data is used to obtain accurate mechanical properties of very thin films or surface-modified layers independently of the properties of the underlying substrates. These procedures accurately deduce the yield strength, elastic modulus, and layer hardness, and greatly increase the usefulness of indentation testing with very thin surface layers. Moreover, extraction of the effective Young's modulus in the near surface region should enable mechanical damage studies on a small scale. This paper presents a brief overview of the procedures involved and illustrates them with He-implanted Ni.
Effect of Moisture on the Mechanical Properties of Pork Rind (Chicharrón)
Authors: Martínez C. González , Corradini M. G. , Peleg M.
Published: October 2003

Pork rind particles of two commercial brands were tested at various water activity levels in the range of 0.1-0.8 and compressed as shallow bed using an Instron universal testing machine. The jaggedness of the resulting force-displacement curves was determined in terms of their apparent Richardson and Kolmogorov fractal dimension and the mean magnitude of their power spectrum after normalisation. The bed's stiffness was assessed in terms of the compressive force at 25 and 35% displacement. The jaggedness decrease, which corresponds to brittleness loss, took place around the water activity of 0.5 with a span of about 0.2. Sorption at levels up to about 0.5 was accompanied by `moisture toughening' that is the bed's stiffness measures increased with aw. There was a sharp decline at higher water activity levels as the structure collapsed. The changes in the brittleness and stiffness parameters as a result of moisture sorption were modelled with the Fermi and a combination of Fermi and the logistic equations, respectively.
Colour Stabilization of Spray-Dried Porcine Red Blood Cells Using Nicotinic Acid and Nicotinamide
Authors: Saguer E. , Altarriba S. , Lorca C. , Parés D. , Toldra` M. , Carretero C.
Published: October 2003

The effect of nicotinic acid (NA) and nicotinamide (NAm) on colour parameters (CIE L*, a*, b*) of spray dried red blood cells and colour stability during a 7-weeks storage period at room temperature were investigated. The influence of pH on the colour of powder stabilized with NA or NAm was also determined by using starch gels as a model matrix. The results showed that nicotinic acid at 2% (w/v) considerably prevented colour deterioration of haemoglobin concentrate during spray-drying as well as during the storage period. The powder obtained was clearer, redder and more yellow than the control. A positive effect was also detected with 2.5% (w/v) nicotinamide, but the improvement achieved was never as high as it was when nicotinic acid was used. However, powder containing nicotinamide at 2.5% (w/v) showed higher capacity as a red colourant than nicotinic acid at 2% (w/v) when added to starch gels either at pH 7.5 or 4.5.
Effect of Thermal Treatment on the Antioxidant Activity and Content of Carotenoids and Phenolic Compounds of Cactus Pear Cladodes (Opuntia ficus-indica)
Authors: Jaramillo-Flores M. E. , González-Cruz L. , Cornejo-Mazón M. , Dorantes-Alvarez L. , Gutiérrez-López G. F. , Hernández-Sánchez H.
Published: October 2003

Cactus pears (Opuntia ficus-indica) are draught resistant plants originated in Mexico. Their flattened stem segments, called cladodes, have moisture, protein and fibre contents of 92, 1-2 and 4-6% respectively, and a pectin content in the range of 0.8-3.3% depending on the species. They also contain certain concentration of carotenoids which are of special interest because of their antioxidant activity. This work is aimed to identify and quantify the main carotenoids present in the stems and to evaluate the effect of thermal treatments on the antioxidant activity and concentration of carotenoids and phenolic compounds. The carotenoids -cryptoxanthin, -carotene and lutein were identified in the cladodes, the latter having the highest concentration. Thermal treatments increased the extractability of these pigments and the antioxidant activity was related to the carotenoids concentration. Total phenolic content decreased after the thermal treatments; however this result had little effect on the antioxidant activity. Mucilage present in the stems decreased the extractability of the carotenoids.
Some Kinetic Properties of Polyphenol Oxidase Obtained from Various Salvia Species (Salvia Viridis L., Salvia Virgata Jacq. and Salvia Tomentosa Miller)
Authors: Gundo[notdef]ggmaz G. , Do[notdef]ggan S. , Arslan O.
Published: October 2003

Polyphenol oxidase (PPO) was partially purified by (NH4)2SO4 precipitation followed by dialysis from different organs of Salvia species (Salvia virgata Jacq., Salvia viridis L. and Salvia tomentosa Miller). Polyphenol oxidase activity was measured spectrophotometrically at 420 nm using catechol as a substrate. Vmax, KM and Vmax/KM values for polyphenol oxidase activity from different organs of Salvia species were determined. S. tomentosa Miller was the species with the highest PPO activity, followed by S. virgata Jacq and S. viridis L. S. tomentosa Miller was the most suitable Salvia species for dark-tea preparations because of the highest Vmax/KM values. The effects of various inhibitors on the reaction catalysed by the enzyme were tested and calculated I50 values, reduced the enzyme activity by 50%. The most effective inhibitor was L-cysteine followed by ascorbic acid. Activation energies, Ea, were determined from Arrhenius equation.
Note: Shelf Life Determination of Korean Seasoned Side Dishes
Authors: Kim Gi-Tae , Ko Yong-Duck , Lee Dong Sun
Published: October 2003

Three Korean side dishes of seasoned beef soup, soybean sprouts and fried tofu were stored at 0, 3 and 10 C. Changes in sensory, physical and chemical indexes were compared with microbial quality deterioration for shelf life determination. For beef soup, shelf life, based on a microbial quality limit of 106 cfu/g, was comparable to that obtained from sensory quality. The primary quality factor criterion for seasoned soybean sprouts determining shelf life varied with storage temperature. For seasoned tofu, shelf life estimates based on a microbial criterion of 106 cfu/g represented a more conservative estimate than those based on sensory quality at 3 and 10 C. Microbial quality was generally to be a common and sensitive criterion for shelf life determination, thus a microbial growth model was used to estimate shelf life at different temperatures.
Extraction and Functional Characteristics of Brazil Nut (Bertholletia excelsa HBK) Globulin
Authors: Ramos C. M. Pinto , Bora P. Singh
Published: October 2003

Proximate analysis of Brazil nut kernel showed 68.6 and 16.5% lipid and protein contents, respectively. The protein content in defatted kernel flour increased to about 46.7%. Extraction with 50mM phosphate buffer containing 0.5 M NaCl (pH 7.2) solubilised about 81% proteins, out of which nearly 72% proteins (globulin) were recovered. Unextracted and soluble proteins accounted for 18.7 and 9.2% of total proteins, respectively. In relation to functional properties, the globulin showed pH of minimum solubility at 5.0. The globulin presented lower solubility (0.9-41.3%) in the pH range of 5.0-10.0 but above and below this pH range, there was a considerable improvement. The water and oil absorption capacities were 2.0 and 1.4 g/g globulin. The apparent viscosity of 1-3% globulin solutions at room temperature (29 [notdef]C) before and after heating at 90 [notdef]C for 15 min differed significantly. However, no significant difference was observed between apparent viscosity of unheated and heated globulin samples irrespective of their concentration. Emulsifying capacity varied with the pH, being maximum at pH 3.0 (94.5 mL/100 mg of globulin) and minimum (38.5 mL/100 mg globulin) at its isoelectric pH (5.0). Emulsion activity and stability also followed similar behaviour as that of emulsifying capacity.
How “Parasites” Serve their Host: A Graphical Analysis of “Scalping”
Authors: Spindler Zane A.
Published: October 2003

Scalpers, as market specialists, may improve ticket-producing firms’ revenues, and the ticket market, when scalpers are relatively limited in number. Thus, both scalpers and firms may have a joint interest in public “scalper regulation” that enhances joint market power. Other market participants may also benefit from a more orderly market.
A Graphical Analysis of “Scalping”: A Reply
Authors: Swofford James L.
Published: October 2003

Swofford (1999) discussed three cases when ticket scalping or other reselling might arise. These cases are reviewed in light of Spindler’s (2003) observation that a perfect price-discriminating ticket scalper could capture all the revenue from the all or none demand curve. Such a price discriminator would have a symbiotic relationship benefiting the original producer of the product. However, the ticket scalper would still have a parasitic relationship with a producer identified more with the product, as such a producer would have customer goodwill in its dynamic revenue function. The original producing firm with goodwill as an argument in its dynamic revenue function might still be a source of agitation for laws against ticket scalping.
The Effect of Public Transfers on Physical and Human Capital Accumulation
Authors: Lin Shuanglin
Published: October 2003

Using a model with heterogeneous agents, this article demonstrates how public transfers affect physical as well as human capital accumulation. An increase in public income transfer from the rich agent to the poor agent will decrease (or increase) both physical and human capital accumulation if the poor agent has a higher (or lower) rate of time preference than the rich agent. An income transfer has no effect on physical and human capital accumulation if the poor agent and the rich agent have the same rate of time preference. A transfer from the rich agent to the poor agent through public education expenditure will decrease the physical capital but may either increase or decrease total human capital depending on the productivity of government education expenditure and other conditions.
The Consequences of Dysfunctional Customer Behavior
Authors: Harris Lloyd C. , Reynolds Kate L.
Published: October 2003

Christopher Lovelock (1994) coined the term jaycustomers to refer to dysfunctional customers who deliberately or unintentionally disrupt service in a manner that negatively affects the organization or other customers. However, to date, no study has explicitly focused on the consequences of such dysfunctional customer behavior. The aim of this article is to advance understanding of the effects of dysfunctional customer actions through concentrating on exploring and describing the consequences of such behavior for those involved in service encounters. In this regard, this study is designed both to respond to recent calls for further research into these issues and to fill this gap in extant knowledge. A review of the literature regarding dysfunctional customer behavior finds limited attention devoted to the effects of such behavior. To explore the nature and dynamics of dysfunctional customer behavior, field research was conducted and extant theory evaluated leading to the development of a propositional inventory and a framework of the effects of such behavior. Briefly, dysfunctional customer behavior was found to have consequences for customer-contact employees, customers, and organizations.