bluuebunny/crossref_metadata_2025 huggingface dataset:
Abscisic acid is correlated with the leaf growth inhibition of four genotypes of maize differing in their response to salinity
Authors: Cramer Grant R. , Quarrie Steve A.
Published: August 2002

In this paper we tested the hypothesis that the leaf growth reduction of
salt-stressed maize is regulated by the abscisic acid (ABA) concentrations in
the growing zone of the leaf. Leaf elongation rate (LER) of maize
(Zea mays L.) was rapidly inhibited by salinity (80 mM
NaCl), and the (+)-ABA concentration increased significantly in the
growing zone of the leaf. Upon removal of salinity, ABA concentrations
decreased rapidly in the growing zone and LER increased to control levels.
Four maize genotypes differing in their responses to salinity were compared
over a range of leaf ABA concentrations. (+)-ABA concentrations in the
growing zone of the leaf were highly correlated with LER inhibition for all
four genotypes. However, the sensitivity of LER to leaf ABA concentrations
differed amongst the genotypes. Thus, for each genotype, ABA concentrations in
the growing zone of the leaf were a good predictor of maize LER response to
salinity.
Fatigue Properties of Steel Cord-Rubber Composite
Authors: Tian Zhenhui , Song Hongwei , Wan Zhimin , Du Xingwen
Published: August 2002

The fatigue properties of [±20°] steel cord-rubber laminated composite under tension-tension (T-T) loading are studied in this paper. The results show that the variation of the cycle strain in the fatigue process under the constant cycle loading exhibits three stages which correspond to damage initiation, steady damage propagation and catastrophic failure. Two-step experiments demonstrate that the strain variation in step-2 generally follows the similar regularity, indicating that the three-stage behavior also exists in that of the defected specimens. The S-N data in the fatigue-life diagram follow a linear trend. Studies on the effect of the frequency on the fatigue properties show that the higher the frequency of loading, the faster the cycle strain increases and the shorter the fatigue life is. The hysteretic loss caused by the viscoelasticity of the constituent materials remains constant during the steady propagation stage of the damage. Both the surface temperature and its increasing rate go up as the maximum stress and the frequency increase.
Differences in Dynamic Performance of Molded Polyurethane Foam as a Function of Pad Thickness and Supported Load
Authors: Neal Brian L.
Published: August 2002

Comfort and durability have evolved into essential performance requirements for the polyurethane foam used in automotive seating. A great variety of tests have been developed in an attempt to measure and predict these properties, both for the foam and the assembled seat. However, the results from these various tests can be quite different depending on the test conditions employed. Furthermore, most tests measure comfort properties at some standard deflection, or pressure, which is nominally designed to represent the average population that will be riding on the seat.

Missing from these tests is a recognition that foam comfort properties are not the same at all deflections, and thus performance and perceived comfort will change as a result of the size and shape of the person riding the seat. This research presents information demonstrating the dependence of comfort properties, such as vibrational transmissivity and quasi-static hysteresis, on foam thickness and foam chemistry. In addition, the effect of pressure is demonstrated using various masses for the transmissivity testing. This work will be analyzed and discussed from the perspective that comfort properties may need to be defined relative to the sitting pressure of the person riding on the vehicle seat.
Interactive Dynamic, Thermodynamic and Electrical Studies on an Electronically Adjustable ER Linear Reversing Mechanism
Authors: Bullough W. A. , Makin J. , Johnson A. R. , Tozer R.
Published: August 2002

An exercise for balancing the heat generated in and the cooling capacity of a digitally operated, clutch based, ER variable motion configuration mechanism is highlighted. Both electrical and mechanical loadings are considered in conjunction with the natural cooling from a rotating cylindrical clutch surface, temperature dependant fluid properties and inertial parameters. The methodology developed applies to both ER and MR type fluids and indicates pointers to the future development of these fluids for high speed machines.
Method of Measuring Thermal Diffusivity of Composites with Thick Fillers and Reinforced Rubbers
Authors: Juma Mohammad , Bafrnec Milan
Published: August 2002

The thermal diffusivity is a property of materials necessary for the mathematical modelling of unsteady heat transfer proceeding during their processing. A new method of measuring thermal diffusivity of solid materials was developed. In estimating the thermal diffusivity of solid materials by this method the experimental temperature field of the sample must be analysed. The values of the thermal diffusivity at different temperatures are obtained by solving the equation of unsteady heat conduction for time variable boundary condition. This method can be applied for composites with thick fillers and reinforced rubbers and enables us to determine the thermal diffusivity of elastomers and reinforced rubbers at temperatures ranging from 20 to 200°C.
Compression of Woven Reinforcements: A Mathematical Model
Authors: Lomov S. V. , Verpoest I.
Published: August 2002

A mathematical model for prediction of the compressional behaviour of woven reinforcement is described. The model accounts for the compression of yarns and the change of yarn crimp under pressure applied to a fabric layer. Compression curves of glass rovings are studied experimentally and serve as input for simulation of fabric compression. The model is tested against experimental data for glass reinforcement for the lower and the higher pressure range.
A New Generation of Materials for the Calendering Industry
Authors: Karjal Teresa P. , Walther Brian W. , Hill Alastair S. , Wevers Ronald
Published: August 2002

While polyvinyl chloride (PVC) has been employed in the calendering industry for many years, other polymers have not been as widely used. Ethylene styrene interpolymers (ESI) demonstrate the requisite rheological properties and thermal stability to be successfully used in the calendering process. Commercial scale validations were performed on ESI based formulations. Examples of the applicability of ESI to calendering are discussed.
Simulation on Natural Smoke Filling in Atrium with a Balcony Spill Plume
Authors: Chow W. K. , Li J.
Published: August 2002

The smoke-filling process in atria of local shopping malls was studied. The scenario of smoke spreading from a shop located adjacent to an atrium was considered. A two-layer zone model, CL-Atrium, was developed with balcony spill plume. Three plume expressions due to Thomas et al. [13], Poreh et al. [12] and NFPA-92B [11] were used and assessed. Comparison was made with simulations due to CFAST. It is found that a condition has to be satisfied for the plume expression due to Thomas et al. [13]. Further, the results on the smoke layer temperature and interface height in the atrium are similar while using the plume expressions by Poreh et al. [12] and Thomas et al. [13].
Analysis of Fire Gases Released from Polyurethane and Fire-Retarded Polyurethane Coatings
Authors: Duquesne Sophie , Le Bras Miche , Bourbigot Serge , Delobel René , Poutch Franck , Camino Giovanni , Eling Berend , Lindsay Chris , Roels Toon
Published: August 2002

We have investigated the analysis of smoke and gases generated under various thermal decomposition conditions of polyurethane (PU) and fire retarded polyurethane coatings. The use of Fourier Transform Infrared Analysis has allowed the continuous detection of a number of the most important fire gases. We have shown that the addition of ammonium polyphosphate (APP) in PU sharply decreases at the same time the emission of toxic gases such as CO or HCN, the optical density of smoke, the weight loss and the formation of soot. Expandable graphite, when added in PU, enables a decrease in toxic gases in a lower proportion than APP. In addition, we note that oxidation reactions strongly influence the nature of the combustion gases in case of fire.
The Flexural Behavior of Woven Prepreg Thermoplastic Composites
Authors: Mariatti M. , Nasir M. , Ismail H.
Published: August 2002

Studies on the flexural damage behaviors of satin and plain continuous-fiber-impregnated thermoplastic (COFIT) prepreg woven composites were carried out. Their weaving characteristics such as float length, interlace region, etc., which are believed to affect composite properties, were determined. It was found that the satin weave exhibits better flexural properties such as flexural strength and modulus than the plain weave system, with a more obvious trend in the 3-ply laminate system. The presence of hole damage significantly influences the damage resistance of the woven system. Both woven systems show a reduction in flexural properties with increasing hole size. In the 3-ply system, due to the greater thickness of the laminate, it was found that the weaving characteristics influence the resin flow and subsequently influence the wetting between the laminates and also affect the composite properties. From the SEM photographs, it was found that the satin weave exhibits better wetting at the interply region, resulting in better flexural properties than the plain weave. In contrast, the plain weave exhibits debonding failure at the interply region, which is obviously observed at the interlace area. This situation might be due to insufficient molding conditions such as molding temperature, time, or pressure. It is obvious therefore that different woven patterns require different molding conditions to obtain optimum properties.
The Year in Review: Rheumatology
Authors: Rozenfeld Vitalina , Chagan Larisa , Kleyman Evgenia
Published: August 2002

Pharmacologic management of rheumatoid arthritis has been a subject of extensive research within the last several years. Novel nonsteroidal anti-inflammatory drugs have entered the arena offering equal efficacy with an improved toxicity profile. The selective cyclooxygenase-2 inhibitors, celecoxib and rofecoxib, are described. New disease modifying antirheumatic drugs include leflunomide, etanercept, and infliximab. Methotrexate, a widely used antirheumatic agent, has been continuously studied with other disease modifying therapies, such as sulfasalazine, hydroxychloroquine, and cyclosporin. Therapeutic principles of rheumatoid arthritis therapy, as well as the role of new treatment modalities is discussed in this review.
Prediction of the Layer Longitudinal Compression Strength
Authors: De Morais A. Balacó
Published: August 2002

This paper presents a new approach to the prediction of the layer longitudinal compression strength of continuous fibre polymer matrix composites. It is known that failure is caused by fibre microbuckling and that the initial fibre waviness and the matrix non-linear behaviour play a major role. A previous model compared very well with experimental results, but required a relatively complex numerical solution procedure. In the present model, the compression strength is obtained by solving a fourth-order polynomial equation. Although based on several simplifying assumptions, the model is in good agreement with the numerical model predictions and with experimental data. Further model simplifications lead to a closed-form expression that seems to be valid for carbon and boron fibre composites.
The Optical Properties of Poly(Ethylene Oxide) Polymer Dispersed Salt Complex
Authors: Ramadin Y. , Ahmad M. , Zihlif A. , Zangana Th. A. , Saq'An S.
Published: August 2002

The optical properties in the UV-visible region of poly(ethylene oxide) thin films containing 0, 10, 20,40 and 50% by weight Dead Sea salts are reported. The obtained optical results are analyzed in terms of absorption formula for non-crystalline materials. From the optical spectra of the given polymeric system, the absorption coefficients have been calculated at room temperature. The values of the optical band width (EOP) have been obtained from direct allowed transitions in k-space. The width of the tail of localized states in the band gap (AE) was evaluated from Urbach-edges. It was found that both energy quantities (E,,P,) and (AE) vary with the concentration of Dead Sea salts dispersed in the polymer matrix. Furthermore, correlation between the energy gaps and the ac conductivity as a function of salt complex concentration is reported.
The Application of Electro-Rheological Fluids to Coaxial Twin Rotary Cylinders and a Shock Absorber
Authors: Kobayashi Kazumasa , Okamoto Kazuki , Okada Naoki , Sato Masayuki
Published: August 2002

As an application of the ERF to a practical device, coaxial twin rotary cylinders, in which the rotation of an inner driving cylinder is transmitted to an outer rotary cylinder through the medium of an ERF, was designed, and the revolution rates of both cylinders were examined. As another application, a simple shock absorber having coaxial cylindrical electrodes without the bypass was designed and the falling time of an inner moving rod was measured.

The quantitative relationship between the applied electric field and the revolution rate and the falling time was obtained experimentally.
Assessment of Compressive Strength of Flexible Composite Materials for Spinal Implantation
Authors: Hudgins R. Garryl , Muzzy John D.
Published: August 2002

This research investigates the ultimate compressive strength of various flexible composite materials. The materials were investigated for replacement of the intervertebral disc, the cartilage in the spine between the vertebrate. Four prototype designs were considered. The laminated and the unidirectional composites were strength sensitive to the wet, simulated physiological environment. These two prototypes failed in shear by debonding between the fiber and matrix. Two braided designs maintained most of their compressive strength in the simulated physiological environment, and their strength was shown to be independent of the presence of an interfacial bond between the braided fibers and the elastomeric matrix.
Parameters Affecting the In-Line Measurement of Gas Solubility in Thermoplastic Melts during Foam Extrusion
Authors: Zhang Q. , Xanthos M. , Dey S. K.
Published: August 2002

The knowledge of gas solubility at processing conditions is of paramount importance for the understanding and optimization of extrusion foaming by gas injection. A recently developed in-line optical method is used to generate data of the solubility of atmospheric gases in PS and PET in single or twin screw extruders with gas injection capabilities. Overall, the in-line data compare favorably with off-line data where Henry’s law constants were obtained from the slope of solubility/equilibrium gas pressure plots. Results obtained with the twin-screw extruder configured for improved mixing indicate a) better data consistency, presumably as a result of enhanced homogenization/dissolution and longer residence time and, b) a higher degree of sensitivity in detecting differences in the solubility of different gases.
Modelling Settling of Loose-Fill Insulation in Walls. Part I
Authors: Rasmussen Torben ValdbjØrn
Published: August 2002

A method is presented for estimating theoretically the necessary density of loose-fill insulation in walls in order to ensure volume stability. Stress analysis for the mass to remain in a stress-stable state and creep of the material have been considered. From stress analysis it is shown to be possible to set up equations to estimate stresses in a granulated insulation material as a function of the height of the wall. These considerations are combined with theories describing creep of a material, thus providing a better understanding of the material behaviour of loose-fill insulation materials in walls. The use of the creep theory is limited to the case for which parameters describing the material are independent of time. For most materials this requires a stable environment and preconditioning. Furthermore, a homogeneous distribution of the loose-fill insulation material is required. The model is experimentally verified in ‘‘Modelling Settling of Loose-fill Insulation in Walls, Part II’’.
Mixed Crosslinking in Chlorosulfonated Polyethylene and its Blend with Ethylene Vinyl Acetate Copolymer
Authors: Antony Prince , Datta S. , Bhattacharya A. , De S. K.
Published: August 2002

Chlorosulfonated polyethylene (CSM) reacts with aluminum oxide in the presence of stearic acid producing an ionic elastomer. Although CSM cannot be cross linked with dicumyl peroxide (DCP) alone, DCP crosslinking can be achieved in the presence of aluminum oxide and stearic acid. Moving die rheometric (MDR) studies show the occurrence of a two-stage crosslinking. In the first stage, the loss component of the torque increases with an increase in the storage component of the torque indicating the formation of ionic crosslinking, whereas in the second step the loss component of the torque decreases along with an increase in the storage component of the torque. The second step indicates the formation of covalent crosslinking. Blends of aluminum salt of CSM and ethylene vinyl acetate copolymer (EVA) were prepared by intensive mixing of the preformed master batches of EVA/DCP and CSM/aluminum oxide/stearic acid. The formation of a technologically compatible blend is due to the interaction between the aluminum sulfonate groups of CSM and the dipole groups present in the EVA, which results in synergism in the tensile strength. Infrared spectroscopic studies reveal that the dipoles of EVA interact with the ionic groups present in CSM.
Improved Equation for Shear Modulus Using Four-Point Ring-Twist Test Data
Authors: Bert C. W.
Published: August 2002

There are numerous test-specimen configurations for determining the static shear modulus of composites. Selection of specimen configuration depends primarily on product component configuration. Two-ring specimens in use are the split-ring twist specimen and the four-point-loading ring-twist specimen. The latter is more advantageous, since it uses an intact ring. However, reported validation tests on aluminum rings showed a large error in predicted shear modulus. The present paper provides an improved analysis that takes into account the tilting of the cross section on the loading bar.
Piezothermoelastic Modeling and Active Vibration Control of Laminated Composite Beams
Authors: Raja S. , Rohwer K. , Rose M.
Published: August 2002

A generalized piezothermoelastic finite element formulation of a laminated beam with embedded piezoelectric material as distributed actuators/sensors is presented. Electromechanical and electrothermal couplings are incorporated using the linear equations of piezothermoelasticity. Inclusion of temperature and electric potential as state variables along with mechanical displacement permits a unified representation of multiple fields coupling in finite element formulations. A two noded 3-D beam element is derived using first order shear deformation theory to model direct and coupled effects. Eigenstructure assignment technique using output feedback is employed in the controller design, which is subsequently adopted to actively control the first three modes of a cantilever PZT/Steel/PZT beam. The desired eigenfrequencies are placed exactly and the tip motion of the beam is significantly reduced by shaping the eigenvectors of the closed-loop system. Control spillover effect is minimized by optimally selecting the actuator/sensor locations and optimizing the damping factors of the desired closed-loop eigenvalues.
A Study on the Buckling and Postbuckling Control of Composite Beams with Embedded NiTi Actuators
Authors: Choi Sup , Lee Jung Ju , Seo Dae Cheol
Published: August 2002

In this paper, an experimental study on the buckling and postbuckling control of a laminated composite beam with eccentrically embedded NiTi actuators is performed. For the purpose of enhancing the critical buckling load, buckling control is investigated through the use of reactive moment associated with the shape recovery force of NiTi actuators. To improve the control authority for the buckling and postbuckling control of the NiTi-composite beam, closed-loop control is used. The buckling and postbuckling control behaviours are presented and discussed qualitatively and quantitatively on load-deflection plots considering stacking sequence of the laminate, slenderness ratio of the beam and activation conditions of the NiTi actuators. The experimental results show that the buckling control can be extended to the postbuckling of the NiTi-composite beam with the proper reactive moment.
A Novel Fiber Optic System for Measuring the Dynamic Structural Behavior of Parachutes
Authors: El-Sherif M. , Fidanboylu K. , El-Sherif D. , Gafsi R. , Yuan J. , Richards K. , Lee C.
Published: August 2002

A novel approach has been developed for real-time characterization of a parachute during inflation. Two techniques were applied to measure static and dynamic stresses in a parachute canopy fabric material and suspension lines: the modal power distribution (MPD) technique and the fiber Bragg grating (FBG) technique. Several tests were conducted under various loading conditions, using a bi-axial tensile tester. The MPD technique was used to measure the transverse stresses in the parachute canopy fabric material and was applied using two experimental set-ups: one using a CCD camera and the other using a photo-detector. The FBG technique was used to measure the axial stresses in the parachute canopy fabric material. The tests were performed using the spectrum analyzer set-up with the bi-axial machine. Finally, a drop test was performed on the parachute canopy fabric material using the MPD technique with the photo-detector set-up.
Finite Element Analysis of Linear Thermal Expansion Coefficients of Unidirectional Cracked Composites
Authors: Islam R. , Sjölind S. G. , Pramila A.
Published: August 2002

The linear thermal expansion of coefficients of unidirectional composites are systematically studied by the Finite Element Method (FEM). Thermal expansion coefficients are first determined for composites with perfectly bonded interface between fiber and matrix. Results are compared with available experimental and analytical results. Next cracks caused by debonding along the fiber-matrix interface are studied to investigate the effects of interface cracking on the transverse thermal expansion coefficients. Due to the presence of cracks and shearing along the debonded interface, the principal direction of transverse thermal expansion changes. The obtained results showthat the transverse thermal expansion coefficients change significantly due to the presence of thin interfacial cracks.
Technology in Education—Where Do We Go From Here?
Authors: Zarotsky Victoria , Jaresko George S.
Published: August 2002

The decreasing cost and rapid growth of technological advances has dramatically impacted the way students are taught and learn in college. Faculty augment their lectures with computer-generated slides, videos and Digital Video Disks (DVD). Computer programs are available to help organize lecture material, provide students with computer assisted learning, provide “real” life cases and simulations, and test the students’ knowledge with computer based exams. New ideas can be accessed and transmitted instantly anywhere in the world with a click of a mouse through the World Wide Web. Guest speakers can be “brought into the classroom” through telephone or video conferencing. Students can obtain degrees, or professionals can get continuing education courses at any time from any place through distance learning. All of these exciting changes have changed the face of what education is like as we proceed into the new millennium. Despite these advances, tests of intelligence have not improved to a significant degree. Nevertheless, most students continue to prefer human-to-human interaction to a technology driven environment. Further training and development of technology in pharmacy education is needed and will continue to be explored.
Actuation and Sensing of Soft Core Sandwich Plates with a Built-In Adaptive Layer
Authors: Abramovich H. , Meyer-Piening H. -R.
Published: August 2002

The present work presents experimental studies performed on soft core sandwich planar plates with a built-in adaptive layer. This adaptive layer consists of an aluminum plate equipped with piezoelectric ceramic transducers (PZT) bonded in pairs on its two faces. The PZT patches can sense deflections using the direct piezoelectric effect (producing charge under the application of stress) and can be also used as actuators to induce deflections to the structure, using the converse piezoelectric effect (inducing shear deformations to the host structure by its stretching or shrinkage under the application of voltage). This new configuration of the sandwich plate has the main advantage of protecting the brittle ceramic transducers by placing them inside the core. The outside sandwich faces then remain unobstructed. The usage of such planar sandwich plates is then discussed.
Development of Fabric Sintering/Compaction Process to Produce Porous UHMW Polyethylene Composites
Authors: Ananthanarayan V. T. , Shutov F.
Published: August 2002

Implants based on solid (nonporous) Ultra High Molecular Weight (UHMW) polyethylene have serious disadvantages such as generation of fine polymer particles, because of the lack of internal natural lubricant inside the implant body. A novel family of porous multilayer composites based on Ultra High Molecular Weight (UHMW) polyethylene commercial fabrics has been developed. These composites are produced using a compaction/sintering process with a compression molding technique. The developed porous materials have much higher tensile strength than solid (nonporous) UHMW polyethylene materials.
Comparison between Non-Destructive Evaluation Techniques and Integrated Fiber Optic Health Monitoring Systems for Composite Sandwich Structures
Authors: Balageas D. , Bourasseau S. , Dupont M. , Bocherens E. , Dewynter-Marty V. , Ferdinand P.
Published: August 2002

Non-Destructive Evaluation (NDE) methods have been adapted to composite sandwich structures in order to detect damage, in particular impact induced damage. Using three coupons representative of radome structures, several techniques were tested: ultrasonics, the Electromagnetic/InfraRed method (EMIR), stimulated shearography and stimulated infrared thermography. The extension of the measured damaged area was taken as a criterion, showing that stimulated shearography and ultrasound are the most sensitive methods. Moreover, two integrated Health Monitoring Systems (HMS) were tested, based on the one hand on microbending sensitive fibres and Optical Time Domain Reflectometry (OTDR), and on the other hand on Fibre Bragg Grating (FBG) sensors. The experiments demonstrated that HMS can detect damage with sensitivity comparable to that of the external NDE techniques.
A Coupled Structural-Magnetic Strain and Stress Model for Magnetostrictive Transducers
Authors: Dapino Marcelo J. , Smith Ralph C. , Faidley Leann E. , Flatau Alison B.
Published: August 2002

This paper addresses the modeling of strains and forces generated by magnetostrictive transducers in response to applied magnetic fields. The magnetostrictive effect is modeled by considering both the rotation of magnetic moments in response to the field and the elastic vibrations in the transducer. The former is modeled with the Jiles-Atherton model of ferromagnetic hysteresis in combination with a quartic magnetostriction law. The latter is modeled through force balancing which yields a PDE system with magnetostrictive inputs and boundary conditions given by the specific transducer design. The solution to this system provides both rod displacements and forces. The calculated forces are used to quantify the magnetomechanical effect in the transducer core, i.e., the stress-induced magnetization changes. This is done by considering a “law of approach” to the anhysteretic magnetization. The resulting model provides a representation of the bidirectional coupling between the magnetic and elastic states. It is demonstrated that the model accurately characterizes the magnetic hysteresis in the material, as well as the strains and forces output by the transducer under conditions typical of engineering applications.
Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels—Two-Year Results with Third-Generation Blowing Agents
Authors: Wilkes Kenneth E. , Gabbard W. Alex , Weaver Fred J. , Booth J. Richard
Published: August 2002

Laboratory data are presented on the effect of constant-temperature aging on the apparent thermal conductivity of polyurethane foam insulation for refrigerators and freezers. The foam specimens were blown with HCFC-141b and with three of its potential replacements—HFC-134a, HFC-245fa, and cyclopentane. Specimens were aged at constant temperatures of 90°F, 40°F, and-10°F. Thermal conductivity measurements were made on two types of specimens: full-thickness simulated refrigerator panels containing foam enclosed between solid plastic sheets, and thin slices of core foam cut from similar panels. Results are presented for the first two years of amulti-year aging study. Preliminary comparisons of measured data with predictions of a mathematical aging model are presented.
Control of Gas Direction in Gas Assisted Injection Molding
Authors: Soh Young Soo
Published: August 2002

An improved method to predict preferred direction of gas in gas assisted injection molding processes is introduced. Resistance of resin flow is defined and this resistance of resin flow is not directly related to the resistance of gas flow. Pressure drop requirement was believed to be proportional to the resistance to gas flow in our previous work. Instead of using the pressure drop requirement, the velocities of the resins should be compared to predict the gas flow direction. This method predicts the gas flow direction from the knowledge of process variables such as resin flow length, cross section area of cavity, melt temperature, and short shot. A simulation package was used to confirm the method.
Behavior of Octopus Muscle (Octopus vulgaris) under a Process of Pressure-Time-Temperature Combinations
Authors: Hurtado J. L. , Montero P. , Borderías J.
Published: August 2002

Octopus muscle ( Octopus vulgaris) of different sex was treated for various different simultaneous combinations of pressure (0.1 or 450 MPa), time (15 or 30 min) and temperature (7, 40, 75 or 100 °C). The sex of specimens was not a significant factor. High pressure was effective in reducing the microbial load and the intense autolytic activity in the octopus muscle. Pressurization time was found to be a significant factor for hardness, but neither hardness nor the exudates were reduced by pressurizing at 450 MPa. Progressive raising of the temperature increased the drip loss, while hardness was reduced only at high temperatures. Increasing temperature produced ultrastructural changes relating to softening, but nevertheless, the ultrastructural changes observed after pressurization did not correspond with modifications in shear strength.
Dilatation and Through-the-Thickness Poisson's Ratio of Composite Laminates
Authors: Yeh Hsien-Liang , Yeh Hsien-Yang
Published: August 2002

In this paper an investigation of the through-the-thickness Poisson's ratio and the dilatation for a general class of randomly-oriented composite laminate is presented. A simple random statistical analysis has been used to demonstrate that under certain conditions, for instance, a laminate with 40 plies or more, the mean values of the through-the-thickness Poisson's ratio and the dilatation in the randomly-oriented laminate are close to those values evaluated from the analytical formulation. Also, the influence of the various lamina material properties E21E1, E31EI, G12/EI, v12, v31 and v32 on the through-the-thickness Poisson's ratio and the dilatation of the laminate are obtained. The results from this statistical analysis provide a set of general guidelines for designing the through-the-thickness Poisson's ratio and the dilatation of the composite laminates to meet various requirements in engineering applications.
Modeling and Control of a Singly Curved Active Aperture Antenna Using Curved Piezoceramic Actuators
Authors: Granger Richard , Washington Gregory , Kwak Seung-Keon
Published: August 2002

There is an increasing need for aperture antenna devices that incorporate multifunctional capability. One popular solution to this problem is the use of an “active aperture antenna” that is able to vary the direction and shape of its radiation pattern by using actuators to alter the shape of the reflector. This study focuses on the use of a pre-curved piezoceramic actuator, referred to as a THUNDER actuator, to change the shape of a prototype reflector. These actuators offer greater force, deflection and higher strength than traditional PZT actuators, while maintaining cost effectiveness. In this study the design of a prototype antenna structure that can accommodate deflection experiments and far-field radiation pattern tests is presented. The theoretical relationship between the dish deflection and the input voltage is established in two stages. In the first stage, the deflection at the end of the actuator is determined using a combination of Hamilton’s principle and laminated composite curved beam theory. The piezoelectric properties of the actuator are also considered during this stage. In the second stage, the deflection at the tip of the dish is calculated using geometric relationships, with the assumption that the remaining portion of the dish moves as a rigid body. The resulting deflection equations yield results that closely match the experimental quasi-static deflection results for a given input voltage, despite the presence of hysteresis. A dynamic model for a THUNDER actuator is developed based on experimental frequency response measurements. Positive Positioned Feedback (PPF) control is implemented on the system, in order to reduce position overshoot and oscillations in the transient response of the structure. The controller yields an improvement in the transient response in both simulation and experiments. Finally, the controlled system is utilized to transmit radiation in the far field.
The Application of Artificial Neural Network (ANN) Technique to Formulation Design of Flame Retardant Polymers—II. Halogen-Free Flame Retardant Polymeric Composites
Authors: Xia Juntao , Wang Jianqi , Huang Congming
Published: August 2002

The application of artificial neural network (ANN) to formulation design of the natural color, halogen-free flame retardant materials was conducted by means of flame retardant expert system (FRES 2.0). This work involves an ANN model with three objects. The optimized outputs, such as LOI, TS and EL were shown to be in good accordance with experiments. An intuitive graphical analysis led to dealing with the correlation between performance and components in formulations, where normally subjected to serious nonlinearity and/or multiobjects. It should be emphasized that together with the three-layered BP (back-propagation) network-based modeling, one can do what can hardly be done before with conventional techniques.
Swelling Properties of Various Polymers Used in Controlled Release Systems
Authors: Vlachou M. , Naseef H. , Efentakis M. , Tarantili P. A. , Andreopoulos A. G.
Published: August 2002

The effect of powder packing and porosity of specimens on the swelling properties of polymeric materials was studied, in various swelling liquids, such as distilled water and 0.1 N hydrochloric acid solution. Capsules, tablets and films of hydroxypropyl methylcellulose, poly(ethylene oxide) and sodium alginate were prepared and their weight uptake after immersion into the above solutions was recorded as a function of time, in order to assess the swelling process. Measurements of some characteristics of the as received powders were also performed as an attempt to classify the specimens prepared according to their porosity.

Within the experimental conditions of this work, it was shown that the porosity of polymeric specimens is a dominant factor that controls their swelling behaviour. Increased porosity leads to fast initial rates of weight uptake and high extent of equilibrium swelling. On the other hand, dissolution and possible degradation of polymers susceptible to acid hydrolysis, results in some variations from the above-mentioned behaviour.

With respect to the application in controlled release systems, the overall delivery rate from a polymeric specimen is expected to be a function of both swelling and disintegration characteristics of a specimen and, therefore, the weight uptake can be considered a measure of the release only in the case of polymers with low water solubility and increased stability to hydrolysis.
Note. Effect of Nixtamal Degermination on Some Physical Properties of Corn Masa and on Sensory Characteristics of Corn Tortillas
Authors: Vidal-Quintanar R. L. , Love J. A. , Johnson L. A.
Published: August 2002

Laboratory-made, whole and degermed corn masa flours (DCM) at 50 and 100% levels were prepared to determine the effects of germs on physical properties and sensory characteristics of masa and corn tortillas. DCM flours were finer in particle size than whole dry masa flour. Whiteness of dry masa flours, calculated as total color difference, increased with degerming. Removal of germs did not modify the dough adhesiveness or the rollability and typical flavor of corn tortillas. The 100% degermed tortillas were significantly more chewy and firm than the whole nixtamal tortilla based on sensory evaluation. Therefore, nixtamal degermination could not be considered as a process to reduce off-odors of stored corn masas.
A New Method to Reduce Cure-Induced Stresses in Thermoset Polymer Composites, Part III: Correlating Stress History to Viscosity, Degree of Cure, and Cure Shrinkage
Authors: Russell John D. , Madhukar Madhu S. , Genidy Mohamed S. , Lee Andre Y.
Published: August 2002

Non-thermoelastic effects such as cure shrinkage of a polymer can play a role in residual stresses in composite parts. Studies have shown that cure shrinkage can place significant stresses on fibers. Therefore, the cure cycle of 3501-6 epoxy resins was modified to change its cure shrinkage characteristics to minimize the stresses. New cure strategies were developed using volumetric dilatometry, differential scanning calorimetry, dielectric cure monitoring, and a unique single fiber stress test method. Cure cycles were modified to balance the resin's thermal expansion with its cure shrinkage. In some cases, a region of constant volume was achieved for a short time. However, the cure shrinkage eventually dominated over thermal expansion in all cycles as the polymer gelled. Changing the cure cycle affected the degree of cure at the point where the fiber/matrix interface developed as well as the amount of cure shrinkage occurring afterwards. A higher degree of cure at this point leads to longer stress relaxation time. Furthermore, less cure shrinkage at this point leads to less stress on the fibers. Also, slow heating rates allow more time for the polymer to relax and relieve stresses caused by cure shrinkage. Finally, a cure cycle that minimizes stresses due to cure shrinkage has been demonstrated.
Polymeric Foaming Simulation for Extrusion Processes
Authors: Shimoda Mitsutaka , Tsujimura Isao , Tanigaki Masataka , Ohshima Masahiro
Published: August 2002

A numerical simulation for polymeric foaming extrusion processes was conducted. Combining classical nucleation rate and bubble growth models with a non-Newtonian fluid model of a flow, a simultaneous bubble nucleation and growth behavior in a flow field was simulated. Simulation results were compared with the experimental data obtained by visual observations at a foaming extruder, where a polypropylene resin was physically foamed. The effects of physical parameters in foaming model on bubble size and number density calculation were intensively examined by sensitivity analysis.
Free Vibrations of Curved Sandwich Beams with a Transversely Flexible Core
Authors: Bozhevolnaya Elena , Frostig Yeoshua
Published: August 2002

A high-order model for free vibrations of singly curved sandwich beams is presented. The model takes into account the transverse flexibility of the sandwich core while the faces of the sandwich are treated as thin beams. Linear equations of motion as well as the natural boundary conditions are derived. Verification of the model is performed for straight beams via a number of asymptotic cases. For the straight and curved sandwich beams, it is shown that there exist four eigenmodes. Their nature is clarified, and simple theoretical estimations for the eigenfrequencies are obtained. A numerical analysis of free vibration of the simply supported beams is carried out. Effects of design parameters of the sandwich constituents on the eigenmodes and their appropriate frequencies are investigated. The developed model may find its use in the context of various applications of curved sandwich members in the high-performance vehicles.
RANDOM SEEKING: A GENERAL, EFFICIENT, AND INFORMED RANDOMIZED SCHEME FOR DYNAMIC LOAD BALANCING
Authors: MAHAPATRA NIHAR R. , DUTT SHANTANU
Published: August 2002

We propose a completely general, informed randomized dynamic load balancing method called random seeking (RS) suitable for parallel algorithms with characteristics found in many search algorithms used in artificial intelligence and operations research and many divide-and-conquer algorithms. In it, source processors randomly seek out sink processors for load balancing by flinging "probe" messages. These probes not only locate sinks, but also collect load distribution information which is used to efficiently regulate load balancing activities. We empirically compare RS with a well-known randomized dynamic load balancing method, the random communication (RC) strategy, by using them in parallel best-first branch-and-bound algorithms on up to 512 processors of a parallel system. We find that the RC execution times are more than those of RS by 16–67% when used to perform combined dynamic quantitative and qualitative load balancing, and by 9–74% when used to perform only dynamic quantitative load balancing.
AN ABSTRACT RADIATION CONDITION AND APPLICATIONS TO N-BODY SYSTEMS
Authors: MØLLER JACOB SCHACH
Published: August 2002

In the setting of Mourre [18] we characterize the "outgoing" and "incoming" solutions, to the abstract inhomogeneous Schrödinger equation (H-E)u=v, given by the Limiting Absorption Principle. The characterization is in terms of an abstract radiation condition and as an application we give a characterization, in the framework of weighted L2-spaces, of the outgoing and incoming solutions for N-body Schrödinger operators with and without Stark effect. The abstract radiation condition translates in the application into a radiation condition considered by Isozaki in [13].
FIRST BETTI NUMBERS OF ABELIAN COVERINGS OF THE COMPLEX PROJECTIVE PLANE BRANCHED OVER LINE CONFIGURATIONS
Authors: TAYAMA IKUO
Published: August 2002

We prove the following results concerning the first Betti numbers of abelian coverings of CP2 branched over line configurations:

(1) An estimate of the first Betti numbers.

(2) A characterization of central and general position line configurations in terms of the first Betti numbers of abelian coverings.

(3) The first Betti numbers of the abelian coverings of the real line configurations up to 7 components.
THE UNUSUAL ADSORPTION BEHAVIOUR OF BENZENE ON ${\rm Co}(10{\bar 1}0)$
Authors: BARNES C. J. , VALDEN M. , PESSA M.
Published: August 2002

Adsorption of benzene on (10[Formula: see text] leads to formation of an ordered p(3 × 1) monolayer. ARPES measurements combined with adlayer density considerations indicate that the [Formula: see text] monolayer consists of molecules whose symmetry has been reduced to C1 consistent with a partially dehydrogenated tilted cyclic C6 intermediate (phenyl or C6H4). Desorption measurements in conjunction with ARPES indicate that a stepwise dehydrogenation of the ring occurs with the dehydrogenation step above room temperature at ~ 380 K corresponding to formation of small well-oriented CxHy (x, y = 1 or 2) hydrocarbon fragment(s) (possibly C2H and CH) resulting from ring opening. Complete dehydrogenation occurs for temperatures above 550 K, leaving a carbonaceous residue. The low dehydrogenation and decomposition temperatures indicate [Formula: see text]0) to be particularly active towards both C–H bond scission and ring opening.
INTERFACE MAGNETIZATION EFFECT IN STRESSED SEMIMAGNETIC HETEROJUNCTIONS
Authors: MALKOVA N. , KANTSER V.
Published: August 2002

A model of the interface magnetization effect based on magnetic properties of the interface Tamm-like states is continuing to develop. The interface spin-polarized states of the stressed heterojunctions formed from the narrow-gap semimagnetic semiconductors with antiferromagnetic ordering are studied in the framework of the two-band envelope function approximation including far-band corrections. The effect of far-band corrections is shown to be conditioned by the mutual movement of the actual bands of the initial semiconductors, resulting in a change of the energy interval in which the interface states exist. Magnetization is expected when the Fermi level lies in one of the interface bands. By the use of appropriate parameters, the value of the relative interface magnetization is calculated.
LARGE CLUSTERS WITH CADMIUM SULFIDE CORES: SIMULATION OF THIOLATE LIGANDS ON THE SURFACE BY Ab Initio MO LCAO CALCULATION
Authors: GURIN V. S.
Published: August 2002

Inorganic cores M n X m (M=Cd, Zn, Cu, etc.; X=S, Se, Te) in the semiconductor clusters produced in solutions with protection by X-containing ligands provide the main physical properties of clusters. However, the external ligand shell is more important in the chemical respect. An effect of the ligand type is considered for a series of Cd nSm– R clusters (n=4, 17 and m=3, 28, respestively, R=H, CH3, CH2OH, C2H4OH) on the basis of ab initio quantum-chemical calculations. Under conservation of local tetrahedral symmetry, the ligand protection strongly influences equilibrium interatomic distances and electronic density distribution. Energies of the first allowed electronic transition for the Cd4S13 species are too high to be fitted in the quantum confinement, while Cd17S28 clusters reveal the value close to the experimental one, which depends on the type of termination.