bluuebunny/crossref_metadata_2025 huggingface dataset:
The Kinetics of Shear-Induced Crystallization in Poly(Ethylene Terephthalate)
Authors: Ahn Seung Hyoun , Cho Chin Bong , Lee Kee Yoon
Published: July 2003

The kinetics of shear-induced crystallization in PET was studied. The shear-treated samples were obtained from Controlled Shear Rate apparatus (CSR, Figure 1) and the capillary viscometer. In the samples were observed the differences of crystallization behavior by DSC. The kinetic model suggested by Hoffman-Lauritzen, Nakamura was used to analyze experimental results.

The crystallization behavior of shear-treated samples depended on temperature and shear stress. On the lower shear rate region, the rate of crystallization depended on shear stress and the growth rate induced by fluid flow reached the critical point in the region of a certain high shear rate. The empirical data were simulated by the suggested model.
Numerical Simulation of Blown Film Cooling
Authors: Sidiropoulos V. , Vlachopoulos J.
Published: July 2003

Commercial blown film production is often limited by the rate of cooling that can be achieved in the production line. The flow of the cooling air around the curved bubble is characterized by rather complex aerodynamics. Even for the same air ring design, different set-ups (adjustable air rings) produce significant differences in the air-flow pattern. Numerical simulation suggests that heat transfer rates are affected by all these parameters. Additionally, numerical simulation in the film phase reveals large temperature gradients across the film thickness in the area where the film is emerging from the die.
Thermal Elastic-Plastic Stress Analysis in Simply Supported Thermoplastic Laminated Plates
Authors: Bektas Numan B. , Sayman Onur
Published: July 2003

In the present study, an analytical elasto-plastic stress analysis is carried out on symmetric cross-ply [0°/90°]2 and symmetric angle-ply [30°/-30°]2, [45°/-45°]2, [60°/-60°]2, thermoplastic laminated plates. Composite laminated plates are simply supported and subjected to constant temperature change through the thickness. The analytical solution is performed for satisfying thermoelastic-plastic stress-strain relations and boundary conditions for small plastic deformations. The composite materials are assumed to be linearly hardening. The Tsai-Hill theory is used as a yield criterion. Residual stress components (σ x) r and (σ y) r for cross-ply laminated plates have some magnitudes but (τ xy) r are zero. The intensity of residual stress components increase gradually depending on the temperature increment. For symmetric angle-ply laminated plates, all residual stresses are found zero.
Foamed Polymer Sandwich Composites Reinforced with Three-Dimensional Filler
Authors: Yuan Y. , Shutov F.
Published: July 2003

Open-pore flexible polyurethane (PUR) foam with varioius pore sizes (1-8 mm) was used as filler to reinforce low-density closed-cell PUR flexible foam. The final composite has a sandwich structure, where the core zone has “foam-in-foam” structure and skin zones are unreinforced PUR foams. Compared to the regular, non-sandwich one-layer PUR flexible foam, the structure composite exhibits improved mechanical properties: the support factor can be increased up to 65 percent and the compressive force deflection value can be increased almost 100 percent while the density of the composite increases only 25 percent.
Determination of the Mode II Fatigue Delamination Toughness of Laminated Composites
Authors: Vinciquerra Anthony J. , Davidson Barry D. , Schaff Jeffery R. , Smith Stephen L.
Published: July 2003

A study was conducted with the aim of determining a criterion for defining the onset of delamination growth for mode II loading using the end-notched flexure (ENF) test, and then using this criterion to develop a mode II toughness versus number of cycles diagram for use in design. Unidirectional graphite/epoxy specimens were fatigue tested in load control at various percentages of the mode II fracture toughness. These tests were stopped whenever a compliance change was observed, at which point the specimens were removed from the test fixture and ultrasonically inspected. The specimens were then returned to the ENF fixture for additional testing, and the process repeated. In this manner, it was determined that a 2% compliance change was necessary for crack advance to occur across a specimen’s full width. Additional tests were then conducted, and the 2% compliance change criterion used, to develop a mode II fatigue initiation toughness curve, i.e., a plot showing fatigue initiation toughness versus the number of loading cycles.
Study of Poly (Ethylene Vinyl Acetate)- Carboxylated Nitrile Rubber (XNBR) Blends with Reference to their Shrinkability
Authors: Chowdhury S. Ray , Das C. K.
Published: July 2003

Heat shrinkability, a collective property, of the polymer is being utilised in various applications - mainly in the field of encapsulation. The elastic memory is introduced into the system in the form of an elastomeric phase. Here, the blends of ethylene vinyl acetate (EVA) and carboxylated nitrile rubber (XNBR) were studied with reference to their shrinkability. It was found that with increasing cure time shrinkability was decreased. On the other hand, with increasing elastomer content, the shrinkage was increased up to a certain level and beyond this shrinkability was decreased. Temperature has a profound effect on the shrinkability. High temperature (H-T) stretched samples showed higher shrinkage than room temperature (R-T) stretched one. Generally, the crystallinity of high temperature (H-T) stretched sample was higher than that of room temperature (R-T) stretched sample, which was again higher than that of original unstretched sample, for a particular blend. At room temperature (R-T), stretching nucleation is favoured but at high temperature (R-T) stretching crystal growth is favoured. From SEM, it was seen that elastomer phase in H-T stretched sample was more elongated than that in R-T stretched one and in shrunk sample elastomer phase was more spherulitic than that of the original unstretched one.
A Micromechanical Model to Study Hygrothermal Shocks at the Fiber-Matrix Interface
Authors: Mukherjee Nilanjan , Aditya Prabir K.
Published: July 2003

Effects of moisture diffusion under thermal shocks on the fibermatrix interface of polymeric composites are studied in this paper. A micromechanical model based on a Galerkin type finite element formulation is developed in cylindrical coordinate system for the study. Moisture diffusivities are assumed to be temperature dependent. Fourier’s heat conduction equation and Fick’s moisture diffusion equation form the basis of the finite element formulation. Single fiber composite models with both moisture impermeable and permeable fibers are studied. The results indicate extremely high moisture desorption rates at the interface due to thermal shocks.
Radial Elastic Modulus for the Interface between FRP Reinforcing Bars and Concrete
Authors: Yu Hailing , Cox James V.
Published: July 2003

The surface structure of reinforcing elements within a matrix can produce a complex mechanical interaction including mechanical interlocking along the interface. This interaction can be modeled using an interface idealization at a scale in which the details of the surface structure are omitted and the actual interface traction is homogenized over a length characteristic of the surface structure. For some applications such as the reinforcement of concrete with FRP bars, the reinforcing element can be idealized as being a circular cylinder, and the radial elastic interaction can affect the overall behavior, e.g., the “bond response” and failure mode of the composite system. The definition of the radial elastic modulus for the interface of the “homogenized model” requires static equivalence of the actual and homogenized tractions and equal amounts of strain energy in the domains. A unit cell approach is taken idealizing the traction distribution as periodic, and an analytical solution for the strain energy in the reinforcing element is presented. The analytical expression for the elastic modulus reflects its dependence upon the traction distribution, material properties, and bar geometry. To study the effects of these parameters, three bond specimens of an FRP bar in a concrete matrix are examined. As the actual traction distribution becomes more concentrated, the interface of the homogenized model becomes more compliant. With respect to material properties, the radial elastic modulus is usually most sensitive to changes in the transverse Young’s modulus of the FRP bar; for lightweight concrete the modulus is equally sensitive to changes in Young’s modulus of the concrete. The elastic moduli are applied to accurately reproduce the effects of a non-uniform traction distribution even when the concrete is split longitudinally and snap-back behavior occurs in the radial response. The traction distribution and compliance of the FRP bar have a significant effect on the snap-back behavior which indicates the potential for a very sudden failure due to concrete cracking.
New Thermoplastic Elastomers by Quasiliving Atom Transfer Free Radical Grafting
Authors: Fonagy Tamas , Ivan Bela , Szesztay Marta
Published: July 2003

Controlled synthesis of a new thermoplastic elastomer (TPE), poly(isobutylene-g-styrene) (PIB-g-PSt) was achieved by quasiliving atom transfer radical polymerization (ATRP). A new commercially available butyl rubber containing bromobenzyl moieties was used as macroinitiator for ATRP of styrene catalyzed by CuBr/2,20-bipyridine complex. Both bulk and solution polymerization resulted in well-defined graft copolymers as indicated by analyses with 1H NMR and GPC. Phase separated morphology in these graft copolymers was found by DSC. Stress-strain analyses indicate high elongation and tensile strength for PIB-g-PSt grafts with certain composition. This new grafting process and the resulting TPE are candidates for several useful applications.
An Elastic-Plastic Stress Analysis of Aluminum Metal-Matrix Composite Beams Supported from Two Ends with a Force Acted at the Mid Point
Authors: KüÇük Mümin , Akbulut Hamit , Esendemir Ümran
Published: July 2003

An analytical elastic-plastic stress analysis is carried out on an aluminum metal-matrix composite beam reinforced by unidirectional steel fibers supported at the ends acted upon with a force at the mid point. The expansion of the plastic region and the residual stress component of x are determined for 1/4 0, 30, 45, 60 and 90° orientation angles. Plastic yielding occurs for 0 and 90° orientation angles on the lower and upper surfaces of the beam at the same distances from the mid point. But, it starts first at the upper surface for 30, 45 and 60° orientation angles. The residual stress components are obtained after releasing the external force. The residual stress component of x is maximum at the lower and upper surfaces. It becomes greater on the boundary of elastic and plastic regions at distant cross sections from the origin. However, the intensity of the residual stress component xy is maximum on or around the x axis of the beam. The beam can be strengthened by using the residual stresses.
Experimental Studies on Impact Behaviour of Woven Fabric Composites: Effect of Impact Parameters
Authors: Naik N. K. , Borade S. V. , Arya H. , Sailendra M. , Prabhu S. V.
Published: July 2003

Experimental studies have been presented on the impact behaviour of plain weave E-glass-epoxy laminates with different combinations of impactor mass and incident impact velocity with the same incident impact energy of 24.43 J. Four combinations of impactor mass-incident impact velocity have been considered. Impact tests have been carried out on an instrumented drop weight impact test apparatus. The unsupported area of the specimens during the impact loading was 127 mm 127 mm with clamped boundary condition. Thickness of the plate was 5 mm. Post-impact-compression testing of impacted specimens has been carried out using Compression-After-Impact test fixture as per NASA 1142 standard. It is observed that for the materials tested, damage tolerance is higher for low mass and high velocity combination as compared to high mass and low velocity combination.
Incompressible Model of Solids Conveying in a Single-Screw Extruder
Authors: Zhang Shibo , Sernas Valentinas
Published: July 2003

Experiments in corn meal extrusion [Zhang, S. and Sernas, V. (1998). Proc. 1998 ASME Int ME. Congress and Exposition, Anaheim, CA, HTD-Vol. 361-1. pp. 309-315] have shown that the flow of solids in the screw channel of a single-screw extruder has a helical pattern. This observation implies that there is a cross-channel velocity component in the solids conveying zone of the extruder. Existing solids conveying models [Broyer, E. and Tadmor, Z. (1972). Polym. Eng. Sci., 12(1): 12-24; Campbell, G.A. and Dontula, N. (1995). International Polymer Process X. Hanser Publishing. pp. 30-35; Darnell, W.H. and Mol, E.A. (1956). Soc. Plast. Eng. J., 12(4), 20-29; Hyun, K.S. and Spalding, M.A. (1997). ANTEC ’97 Proc. 163: 211-218] treat the solids moving in the channel as a plug flow without a cross-channel velocity component. The two-dimensional powder conveying model proposed in this paper contains both a down-channel component and a cross-channel component. The stress generating mechanism is much more complicated in a powder flow than in a fluid flow. The incompressible model incorporates a constitutive equation for the powder flow with slip boundary conditions. The energy equation with appropriate boundary conditions is also included in the model.

The numerically solved model shows that the predicted down-channel pressure development, velocity and temperature distributions are all reasonable.
Bounds on Transverse Modulus of a Multiphase Composite
Authors: Sharma Rajesh , Ranjan Ashish , Sharma Adhiraj
Published: July 2003

Minimum and maximum values of transverse modulus are obtained for a multiphase composite body when its modulus in longitudinal direction is prescribed and the moduli of constituents take values in a given finite interval. Similar bounds are deduced for the longitudinal modulus of the composite when its transverse modulus is prescribed. The constituents of the composite are assumed to be homogeneous and isotropic.
Free Vibration Analysis of Two Layered Cross-Ply Laminated Beams Using Layer-Wise Trigonometric Shear Deformation Theory
Authors: Shimpi R. P. , Ainapure A. V.
Published: July 2003

In this paper, variationally consistent layer-wise trigonometric shear deformation theory (LTSDT) has been extended to deal with free vibration of two-layered laminated cross-ply beams. In this displacement based theory, constitutive relations between shear-stresses and shear-strains are satisfied in both the layers, and, therefore, shear correction factor is not required. In-plane displacement is such that the resultant of normal stress acting over the cross section is zero. Compatibility at the layer interface in respect of in-plane displacement is also satisfied. Present theory contains even less number of unknown variables than those of the first order shear deformation theory (FSDT). In the present formulation, effects of rotary inertia and other inertias are also included. The efficacy of the present theory is demonstrated through the illustrative example.
A Study on Biodegradable Composite Prepared from Jute Felt and Polyesteramide (BAK)
Authors: Dash B. N. , Sarkar M. , Rana A. K. , Mishra M. , Mohanty A. K. , Tripathy S. S.
Published: July 2003

Jute-polyesteramide(BAK) composite specimens having 45, 50, 55, 60 and 65% of jute by mass were prepared following film stacking method by compression molding technique. It was found that with increase in jute content, the flexural strength and modulus increased from 25.89 and 4709 MPa (45% jute) to 41.75 and 8613 MPa (60% jute) respectively and thereafter decreased with higher loading of fiber. For tensile strength and modulus, the same trend was observed. At 45% jute content, the values were 33.61 and 2599 MPa respectively, whereas at 60% jute content the values were 41.23 and 3346 MPa respectively. The thermogravimetric analysis of jute felt, BAK film and jute-BAK composites (60% jute) were made. The biodegradability of the composite specimens were studied by soil burial test, IR and SEM analyses.
Progressive Failure Analysis of Laminated Composite Plates by Finite Element Method
Authors: Pal P. , Ray C.
Published: July 2003

The progressive failure analysis of laminated composite plates under transverse static loading has been carried out in linear and elastic range. The laminated composite plate has been modeled using eight noded isoparametric plate bending elements. The first order shear deformation theory has been applied and a shear correction factor is used. After the failure of the weakest ply, the stiffness is reduced by either fiber failure or matrix failure. The stiffness of failed lamina has been totally discarded and other existing laminae are considered to remain unchanged after the weakest ply failure. The strength of the laminate at the same point is evaluated again to see if the laminate can carry additional load. This ply-by-ply analysis progresses until the ultimate strength of the laminate is reached. The results in terms of first-ply failure load obtained in the present investigation have been compared with those available in published literature. A parametric study has been done on the progressive failure analysis.
Analysis of Thin-Walled Composite Beams with Arbitrary Layup
Authors: Kollar Laszlo P. , Pluzsik Aniko
Published: July 2003

A beam theory for open and closed section, thin-walled, composite beams is presented. The layup of each wall segment is arbitrary, the effects of shear deformation and restrained warping are neglected. Closed form expressions are developed for the calculation of the 4×4 stiffness matrix. It is also shown that the local bending stiffnesses of the wall segments may be neglected when the laminate is either symmetrical or orthotropic.
Finite Element Analysis of Composite Wing T-Joints
Authors: Kumari Shyama , Sinha P. K.
Published: July 2003

The present paper is concerned with numerical studies of composite T-joints which are made of carbon fibre composite (CFC) materials. CFC materials are used due to their high load carrying capacity and lightweight. The composite T-section is formed at the spar-lower skin joint section in aircraft wings. The behaviour of such joints is very complex. In this study, a brief account of the problem is first presented and areas of principal interest which most influence joint behaviour are identified. A thick composite shell finite element is specially developed and it is then used for a detailed finite element analysis of composite T-joints. Though several types of forces act on the spar, in the present case, a pull-out force is applied on the top of the web to determine strength and to study the behaviour of T-joints. Parametric variations account for two different stacking sequences and variations in filler area and radius of curvature at the web/skin interface. Accuracy of the present finite element analysis is established by comparing present results with the published ones. Numerical results obtained through parametric variations are presented and discussed to understand the joint behaviour.
Carbon Black Filled Silicone as a Compliant Thermoelectric Material
Authors: Kowalik Daniel P. , Chung D. D.L.
Published: July 2003

A compliant silicone-matrix composite containing carbon black and exhibiting volume electrical resistivity 2.3 Ω cm was found to exhibit absolute thermoelectric power + 2 μV/°C.
Study on Bentonite-Unsaturated Polyester Composite Materials
Authors: Abu-Jdayil Basim , Al-Malah Kamal , Sawalha Ranya
Published: July 2003

Jordanian Ca-bentonite was used in formulation of unsaturated polyester-based composite materials. For curing purpose, methyl ethyl ketone peroxide was used as an initiator and it was accelerated with cobalt octoate to maximize the curing process at room temperature. The effect of filler and styrene contents on the physical properties of composites was assessed by measuring the compressive strength, hardness, thermal conductivity, water absorption capacity, and apparent density. Increasing the filler content, at a constant styrene/polyester ratio, increased the properties of composites. On other hand, maximum values of compressive strength, hardness, and thermal conductivity of composites were found at about 22.7 wt% of styrene, whereas water absorption capacity was minimum at a styrene content of 32.8 wt%. Nevertheless, the apparent density was found to linearly decrease with styrene content.
Tensile Properties of Glass Rovings/Hydroxyl Terminated Polyester Toughened Epoxy Composites
Authors: Rajulu A. Varada , Kumar S. V. Sanjeev , Rao G. Babu , Shashidhara G. M. , He Jiasong , Zhang Jun
Published: July 2003

Epoxy was toughened with 5% hydroxyl terminated polyester and different layers of glass woven rovings were reinforced into this matrix. Their tensile strength was determined. The variation of the tensile strength with weight fraction of the rovings was studied. The tensile strength was found to increase with rovings content. The morphology of the cryogenically fractured surfaces indicated good bonding between the matrix and the reinforcement when a coupling agent was used.
Evaluation of a Calcium- and Protein-Fortified Pasta Designed for the Older Population
Authors: Smith Terra L. , Knight Sue
Published: July 2003

A high-protein, high-calcium pasta developed to help meet the nutritional needs of the elderly was fed to experimental animals to determine whether added nutrients were absorbed and used. To test whether the 17% protein in the pasta inhibited calcium absorption, two pasta diets were fed. To test for protein use, two marginal protein diets were used. For the pasta diets, the higher protein diet produced greater weight gain, fecal measures, carcass protein, and tibia but a lower protein efficiency ratio. For the 10% marginal protein diets, fecal protein and carcass energy were significantly greater for the 10% protein pasta diet when compared with the casein-based diet but the carcass protein was significantly lower. Protein was well absorbed and used from the pasta diets. Furthermore, the 17% protein pasta diet supported adequate rat growth without diminishing bone parameters.
Expected and Actual Difficulties of Volunteer Resident Advocates in an Ombudsman Program
Authors: Keith Pat M. , Schafer Robert B.
Published: July 2003

Much of the oversight in federally mandated ombudsman programs in nursing facilities is accomplished by volunteers. This research compared anticipated difficulties of volunteer resident advocates in an ombudsman program prior to their participation with those they actually experienced. Data were analyzed from an application form ( n = 694 applicants) and a mail questionnaire ( n = 700 volunteers). Applicants substantially underestimated the amount and type of difficulties they would experience. Incongruence between applicants' anticipated difficulties and those they later reported suggested areas for training and implications for practice.
Cognition and Perceived Social Support Among Live-Alone Urban Elders
Authors: Ficker Lisa J. , MacNeill Susan E. , Bank Adam L. , Lichtenberg Peter A.
Published: July 2003

The relationship of cognition to perceived social support (PSS) was examined in a sample of 188 older medical patients who lived alone before admission to the hospital. Most of the patients were African American, and a majority (54.3%) was classified as cognitively impaired based on their performance on the Mattis Dementia Rating Scale. Compared with cognitively intact elders, impaired participants reported lower overall PSS as well as lower PSS in their relationships with friends and significant others. These findings suggest that cognitive functioning is an important factor in influencing older, medically ill African Americans'perceived social support. Possible risk factors for low PSS and the role of cognition in friendship and maintenance of a social support network are discussed.
Psychological Outcomes of Preparation for Future Care Needs
Authors: Pinquart Martin , Sörensen Silvia
Published: July 2003

Influences of four aspects of preparation for future care needs (becoming aware of the risk of needing future care, gathering information about care options, deciding on preferences, and concrete planning) on levels of worrying, depression, and satisfaction with preparations were investigated in 573 older German adults. Whereas becoming aware was associated with higher levels of worrying and depression, gathering information and concrete planning predicted lower levels of worrying and depression and higher levels of satisfaction with preparations. Three styles of coping with future care risks were identified: avoidance, thinking about future risks without planning, and concrete planning. Avoiders had lowest levels of worries and depression, whereas planners were most satisfied with their preparation activities. Thinking about future risks without making concrete plans was associated with the lowest levels of psychological wellbeing. Results indicate thinkers or nonplanners should be the main target of intervention to promote preparations for future care needs.
Negative Affectivity and Emotion-Focused Coping in Spouse Caregivers of Persons With Alzheimer's Disease
Authors: Butt Zeeshan A. , Strauss Milton E. , Smyth Kathleen A. , Rose-Rego Sharon K.
Published: July 2003

Several studies have noted that spouse caregivers'negative affectivity, or neuroticism, is associated with the use of emotion-focused coping strategies. This association may be artificially inflated, however, due to the common mode of assessment used in these studies or to the reactive relationship between negative affectivity and coping. To address this issue, this study examined the relationship between self-reporting and informant reporting of negative affectivity and selfreported coping. Informants, adult children (N = 39) of caregivers, completed the NEO–Five Factor Index, in which they described their caregiver parent prior to the onset of dementia in their other parent. Caregivers completed measures of current coping and distress. Only emotion-focused coping showed a tendency to be more highly correlated with self-reported than with informant-reported negative affectivity. Correlations between self-reports of negative affectivity and use of emotion-focused coping may reflect a reciprocal interaction between these two variables and therefore may overestimate their association.
Met and Unmet Need for Medicaid Home- and Community-Based Services in the States
Authors: Harrington Charlene , LeBlanc Allen J. , Wood Juanita , Satten Norma F. , Tonner M. Christine
Published: July 2003

This study examined the met and unmet need for Medicaid personal care services (PCS) and home- and community-based service (HCBS) waivers across the states. Medicaid directors and state officials working with PCS and HCBS were interviewed by telephone in l998-1999 to collect descriptive and statistical data. A total of 26 states offered PCS to 467,487 participants in l998-1999, and 49 states offered waiver services to 561,510 participants in l997. In spite of wide variations in total HCBS participants per capita, 42 states reported inadequate waiver slots and waiting lists. Even in states with the highest participant rate per capita, state officials reported waiting lists for theHCBSwaiver programand many target groups that were not adequately covered by the current HCBS waivers. A number of barriers existed to expanding HCBS services, including an inadequate supply of home- and community-based providers, limited state legislative support for the programs, and federal regulatory barriers such as restrictions on need criteria.
Experimental Study on the Effectiveness of the Extinction of a Pool Fire with Water Mist
Authors: Xishi Wang , Guangxuan Liao , Jun Qin , Weicheng Fan
Published: July 2003

In order to study the effectiveness of the extinction of a pool fire with one nozzle water mist, a series of experiments were conducted under different conditions in an open space. Fire sources are small-scale circular stainless steel pans of 130 and 200 mm in diameter with the fuel of alcohol and kerosene. Before and after the application of water mist, some K-type thermocouples along the pool centerline and a digital camera were used to measure the flame temperature and visualize the process of the fire extinction. A thermogage and a turbine flux sensor were used to measure the flame radiant heat flux and the application rate of water, respectively. A Particle Image Velocimetry and Sizing (PIVS) technique was developed to characterize the water mist. The experimental results show that both the flame of alcohol and kerosene cannot be extinguished in many cases when the pressure is lower than 0.4 MPa. In addition, the distance between the flame and the nozzle, and the application rate of water are two main factors which influence the effectiveness of the extinction of a pool fire when the working pressure is lower and the impulse injection of water mist can improve the effectiveness of fire extinction. However, it should be noted that the results are limited to the experimental conditions because it is still difficult to get the functional relationships of pool fire extinction mechanisms with water mist.
Preliminary Studies on Burning Behavior of Polymethylmethacrylate (PMMA)
Authors: Zeng W. R. , Li S. F. , Chow W. K.
Published: July 2003

The burning behavior and combustion mechanism of polymethylmethacrylate (PMMA) were studied by using cone calorimeter, mass spectrograph and gas chromatograph. Main combustion mechanisms of PMMA were reviewed. Results indicated that PMMA would burn steadily under low radiative heat flux; or with thicker samples. The yields of carbon dioxide and carbon monoxide would not be changed. Under high heating rate, there are three broad stages. Firstly, upon heating by external sources, PMMA would decompose to generate monomer MMA and a small amount of other products. Secondly, monomer MMA would decompose to produce small molecule products. Finally, these small gaseous molecules would undergo oxidation, i.e., burning. The main oxygen consumption reaction, i.e., the heat release reaction, is the burning of small molecule products. Main combustion products are found to be carbon dioxide and water, with a small amount of carbon monoxide. At high temperature, the monomer MMA would react with oxygen directly to produce methyl pyruvate, formaldehyde and acetone. However, these reactions are not important in the combustion process of PMMA.
Assessment on Heat Release Rate of Furniture Foam Arrangement by a Cone Calorimeter
Authors: Chow W. K.
Published: July 2003

Heat release rate of a typical furniture foam sofa was assessed with a cone calorimeter. The sofa arrangement included two layers of fabric, cotton and foam. Individual component materials and combination of them were tested. A high radiative heat flux of 50 kW m 2 was used to consume all materials in the tests. The sustained ignition time, peak heat release rate and total heat release rate were deduced from the heat release rate curves. These data are useful for classifying the materials by calculating two parameters describing the possibility to flashover. The superposition of heat release rate curves and total heat released (THR) were studied. It is observed that adding the heat release rate curves for component materials would not give the heat release rate curve of a furniture arrangement with different combinations of materials. However, the THR for the components can be added to give the THR of the arrangement.
Fire Retardant Synergism Between Cyclic Diphosphonate Ester and Melamine in Poly(Butylene Terephthalate)
Authors: Balabanovich A. I. , Levchik G. F. , Levchiky S. V. , Engelmann J.
Published: July 2003

A cyclic diphosphonate ester and melamine have provided excellent fire retardant performance in poly(butylene terephthalate) (PBT). An increase of the oxygen index as well as an improvement of the UL-94 classification to V-0 rating was observed. The interaction between the fire retardant additives and PBT was studied by thermal analysis and infrared spectroscopy. Aromatic nitriles were detected in the solid residue and in high boiling products of the thermal decomposition of the fire retardant polymer. Synergism between cyclic diphosphonate ester and melamine is discussed in terms of chemical interaction of the additives with PBT.
Detailed Structure and Stabilization Mechanism of Lifted Laminar Methane Flame
Authors: Kim Hoo-Joong , Kim Yong-Mo
Published: July 2003

The present study has numerically investigated the lifted flame field frequently encountered in the actual fire situations. This study employs the physical submodels including the detailed chemical kinetics, the variable transport properties, and the radiation model. A lifted laminar CH4/air flame with a central diluted fuel jet and a surrounding fuel-lean coflow is chosen as a validation case. Computations are done for three models which include the detailed chemistry model considering the radiative heat loss, the detailed chemistry model neglecting radiation, and the single-step irreversible chemistry considering radiation. Among three models, the detailed chemistry model considering the radiative heat transfer yields the best conformity with the measured velocity distribution. Numerical results indicate the present approach well captures the detailed structure and stabilization mechanism of the partially premixed triple flame.
Blends of Wool with High Performance Fibers as Heat and Fire Resistant Fabrics
Authors: Bourbigot Serge , Flambard Xavier , Ferreira Manuela , Poutch Franck
Published: July 2003

The heat and flame resistance of the high performance fibers poly- p-phenylenediamine-terephthalamide (PPTA), co-poly( p-phenylene-3,4-oxidiphenylene-terephthalamide) (TECH) and Poly( p-phenylene-2,6-benzobisoxazole) (PBO) fibers is studied. It is shown that for an organic polymer PBO has exceptional heat and fire resistance. Blends of wool with high performance fibers is studied in order to investigate possible synergistic effect. Blends of wool with PBO do not enhance the FR performance of wool. Blends of wool with p-aramides (PPTA and TECH) improves the FR performance and the thermal stability of the whole textile. Synergistic effects are suggested in terms of Rate of Heat Release (RHR) peak. A mechanism of action explaining the enhanced performance is proposed.
Experimental Study on Scale Effect on Mass Loss Rate of Some Woods
Authors: Lizhong Yang , Zaifu Guo , Jingyan Zhang , Xiaojun Chen , Zhihua Deng
Published: July 2003

Experimental measurements have been done for mass loss rate of some woods usingcone calorimeter and radiation platform for studying fire performance of materials at early stage, respectively. The experiments have indicated that both sample scale and apparatus scale affect the mass loss rate obviously. Generally, average mass loss rate of larger sample is higher than that of smaller sample. Scale has little effect on the first peak of mass loss rate, but it shows a distinct effect on the second peak. The second peak of mass loss rate of larger sample is much higher than that of smaller sample. There may be a critical sample size for the second peak existence. The sample in cone calorimeter can be ignited easily with stable and long time continuous flame compared with radiation platform under the same heat flux.
On the Operation Time of Horizontal Ceiling Vent in an Atrium
Authors: Li Y. Z. , Huo R. , Chow W. K.
Published: July 2003

Smoke control by a horizontal ceiling vent in an atrium is studied in this paper. A bi-directional airflow moving upward and downward across the vent might be observed and this would affect the efficiency of smoke extraction. Whether the flow is bi-directional or uni-directional depends on the pressure difference across the vent upon activation. Before opening the horizontal ceiling vent, the pressure difference should be higher than a critical value. Thickness of the smoke layer formed under the ceiling before opening the vent is found to be important. The required smoke layer thickness for getting such a critical pressure is discussed in this paper. Two situations of no temperature difference between the inside and outside of the atrium; and the outside temperature is higher than the inside temperature, are considered.
Preliminary Studies on Flashover Mechanism in Compartment Fires
Authors: Liang F. M. , Chow W. K. , Liu S. D.
Published: July 2003

The mechanism of flashover in a compartment fire is investigated using nonlinear theory through a two-layer zone model. To simplify the illustration of the approach, there is only one variable, i.e. the upper smoke temperature, with the smoke layer interface height being fixed. Effects of different factors, such as the geometry of the compartment, the thermal and chemical properties of the combustible content, and the ventilation conditions, affecting flashover are discussed. Results show that the occurrence of flashover depends on many factors, among which, heat release rate is the most important.
Study of Refrigerant Leakage in Refrigeration System
Authors: Zhao Yang , Shigang Zhang , Guansan Tian , Bin Liu , Yitai Ma
Published: July 2003

In this paper, a method to calculate the leakage of the flammable refrigerants in the refrigeration system by simplifying the leaking process using hydromechanics is put forward. Based on the efflux theory, it also calculates the velocity and concentration fields of the refrigerant, and points out the existance of FOECA.
Discussion on Two Plume Formulae with Computational Fluid Dynamics
Authors: Chow W. K. , Yin R.
Published: July 2003

Two plume formulae commonly used in fire safety engineering design were assessed by simulating the aerodynamics induced by a fire. The self-developed fire field model CY-TEAM, based on a modified two-equation k-" turbulence model, was used to predict the air flow and temperature field. Twelve simulations of varying heat release rate and perimeter of fire, with bounded and unbounded ceiling, were carried out. It is found that the power law for the mass flux with height holds. At the plume region, the two equations for mass flux would give the same result for those fires with heat release rate related to its perimeter. Results were compared with experimental data and with another set of simulations with finer grids. Further, part of the results are compared with those predicted by the new fire field model FDS based on large eddy simulation developed at Building and Fire Research Laboratory, National Institute of Standards and Technology, USA. Good agreement among k-" turbulence model, large eddy simulation model and experimental data were found. A further verification on CY-TEAM in studying plume induced by heptane pool fires was reported.
Burning Characteristics of Non-Spread Diffusion Flames of Liquid Fuel Soaked in Porous Beds
Authors: Kong Wenjun , Chao Christopher Y. H. , Wang Jinghong
Published: July 2003

An experimental study was conducted to investigate the effects of sand size and sand layer depth on the burning characteristics of non spread diffusion flames of liquid fuel soaked in porous beds. Sand beds with sand sizes from 0.12 to 3.18 mm and sand layer depths from 50 to 80 mm were chosen as the porous beds. Pure methanol was used as the liquid fuel. The flame appearances and effects of sand sizes and sand layer depths on flame temperature profiles, locations of vapor/liquid interface, vapor region moving speed, combustion duration time, fuel consumption and amount of fuel residues in the porous beds were studied in the experiments. An approximate analytical model based on the assumption of a two-phase Stefan problem was employed to predict the fuel consumption rate and the interface location. This model can quantitatively predict the interface position of combustion of the liquid fuel in the porous bed. The predicted results can also confirm that heat transfer in the bed is the controlling mode at the beginning stage of the combustion. After that, capillary force acts as the dominant role for diffusion of the vapor upward.
Study on the Thermal Degradation of Cellulosic Fibers Treated with Flame Retardants
Authors: Xu J. Z. , Gao M. , Guo H. Z. , Liu X. L. , Li Z. , Wang H. , Tian C. M.
Published: July 2003

The thermal degradation in air of hemp fabric treated with various compounds containing nitrogen, phosphorus, halogens, and boron, in combinations of two compounds, has been studied by differential thermal analysis and thermogravimetry from ambient temperature to 600 C. The kinetic parameters were obtained using the equation of Broido. The values of activation energies for the oxidative decomposition of samples were found to be in the range 52-102 KJmol 1. Hemp fabric treated with flame retardants showed a high limiting oxygen index and char yield which indicated that the flame retardance of treated hemp was improved. Effect of the different elements on degradation behaviors has been proposed.
Efficacy of a Computer-Assisted Instruction Program in a Prison Setting: An Experimental Study
Authors: Batchelder John Stuart , Rachal John R.
Published: July 2003

The efficacy of using computer-assisted instruction (CAI) with inmates participating in a prison education program was examined through an experimental study. The researchers sought to address and correct many of the methodological flaws commonly present among studies that compare a CAI-plus-traditional-instruction combination to traditional-instruction alone. Seventy-one inmates were randomly assigned to either an experimental group that received a CAI-plus-traditional-instruction combination, or a control group that received traditional instruction only. Achievement scores of inmates in the experimental group were not significantly higher than those in the control group.
We'll Never Turn Back: Adult Education and the Struggle for Citizenship in Mississippi's Freedom Summer
Authors: Rachal John R.
Published: July 2003

In the summer of 1964, several civil rights organizations, led by the Student Non-violent Coordinating Committee, formed a coalition and conducted a voter registration and educational program in Mississippi, which became known as Freedom Summer Continuing the civil rights work that preceded it, Freedom Summer was distinguished by its organized, statewide, and highly public attempt to promote its three-pronged educational program of freedom schools, community centers, and voter registration, and by the recruitment of several hundred out-of-state student volunteers to implement the program. Adult education played a critical role in the schools, the centers, and the voter registration work, and included literacy education, practical skills, and political awareness. Paulo Freire's work in adult education in Brazil and his paradigm of critical consciousness provide an intriguing historical parallel as well as a useful theoretical frame from which to analyze the adult education component of the Summer Project. Confronted with verbal, legal, and sometimes violent hostility, Freedom Summer sought to use education and moral suasion to give democracy and citizenship a more genuine meaning.
Critical Reflections on Mentoring in Work Settings
Authors: Darwin Ann
Published: July 2003

Mentoring is presently at the forefront of strategies to improve workplace learning. However as is often the case, functionalist models of mentoring dominate, and as a result, research on mentoring is rather narrowly conceived. This article was designed to redress this imbalance by critically reflecting on mentoring from contrasting theoretical perspectives. Functionalist conceptions of mentoring construct it as a rational and hierarchical process, often involving an older mentoranda younger learner In contrast, critical or Radical Humanist conceptions highlight contests for meaning but, more important, want to expose unequal and often exploitative power relations. Many mentoring relationships undoubtedly involve high levels of nurturance, but as this article demonstrates, taken-for-granted practices need to be brought to the surface for mentoring to be regarded as a useful learning tool in today's work settings.
Searching for a Path out of Poverty: Exploring the Achievement Ideology of a Rural Community College
Authors: Valadez James R.
Published: July 2003

Nationally, educational institutions are responding to changes in the postindustrial economy by emphasizing the preparation of students to enter more highly technical jobs. Schools and colleges look toward strengthening their graduates by tying classroom work more closely with the skills students need to be successful in the workplace, by emphasizing workplace values, and by teaching on-the-job behaviors that employers find desirable. In this study, a group of rural African American women entered a community college work program to seek the skills they needed to escape the welfare rolls and to prepare themselves for jobs in their community. Pierre Bourdieu's concept of "habitus " was used to help explain the contradictions and complexities in the daily lives of these women as they struggled to overcome their difficult situations and faced decisions about their futures in a rural community offering few options for long-term employment.
Expanding Conceptions of Experiential Learning: A Review of the Five Contemporary Perspectives on Cognition
Authors: Fenwick Tara J.
Published: July 2003

This article offers a comparison of five distinct currents of thought apparent in recent scholarly writing addressing experiential learning, defined here as a process of human cognition. These five perspectives were selected for their heuristic value in expanding conventional notions of experiential learning, ranging from conceptions of reflective constructions of meaning to psychoanalytic, situated, emancipatory, and ecological theories of learning. A rationale for this typology is outlined, and the problems of classification and comparison of multiple perspectives are discussed. The five perspectives are each described briefly, outlining their view of knowledge, learning, and teaching; their understanding of relations between knower, culture, and knowledge; and critiques and questions raised by other perspectives. Caveats about the limitations and presumptions of such a typology are declared along with invitations for response and critique.
The Politics of Consumer Education Materials Used in Adult Literacy Classrooms
Authors: Sandlin Jennifer A.
Published: July 2003

This study examined the consumer education texts used in adult literacy programs to determine how they portray adult literacy learners as consumers and how they depict the consumer market in which learners operate. It was concluded that the hidden curriculum of the texts promotes several ideologies that are disrespectful of adult learners and that work to maintain or reproduce current class inequalities through placing blame for financial failure on learners and ignoring larger social, political, and economic contexts.
Workers' Education and Neoliberal Globalization: An Adequate Response to Transnational Corporations?
Authors: Salt Ben , Cervero Ronald M. , Herod Andrew
Published: July 2003

Believing that education is vital to improving the conditions of workers in the globalized economy, this study assesses the work of 10 leading worker education programs. The place of globalization in the programs and their stance toward international solidarity are analyzed, and the programs are ranked by using criteria to determine whether they are engaging in what the authors call "transformatory education" or "accommodatory education" with regard to neoliberal globalization. Case studies of the United Auto Workers-General Motors' (UAW-GM) paid educational leave, the American Federation of Labor and Congress of Industrial Organizations' (AFL-CIO) Common Sense Economics, the International Federation of Workers' Education Associations' (IFWEA) international study circles, and other programs show the strengths and flaws in contemporary workers' education. Arguing for a more cohesive response to confronting the transnational corporation-dominated global economy, this article presents a critically reflective approach that can be used by all social movement organizations concerned with globalization.