bluuebunny/crossref_metadata_2025 huggingface dataset:
Latin American Electric Power Developments and Hydrocarbon Demands
Authors: Sierra Gabriel Sanchez
Published: July 2017

Latin American countries must address issues such as financing, management (business, technical, environmental) and low-income sectors to promote the structural changes required in energy supply and demand to optimise efficient use. Private sector participation is not only a matter of ownership but raising the level of efficiency. The state's role will be to ensure stability, confidence and environmental safeguards.
Corporate Renewal in the Natural Gas Industry
Authors: Simpson Bruce
Published: July 2017

Nova Corporation has four companies for transmission, services, chemicals and the international for its operations in natural gas competitively and worldwide.

The business transformation of Nova Gas Transmission for competitiveness and customer service is described in detail. The criteria used were: lowest cost, reliability, simplicity, dependability, flexibility and information.
Foreign Investment Opportunities in the Venezuelan Upstream Industry
Authors: Pradas Francisco
Published: July 2017

Venezuela with 64 billion barrels of proven reserves, estimates that 40 billion barrels of light and medium crudes are to be discovered. Petroleos de Venezuela medium term plans call for big investments and includes the establishment of associations with private enterprises which can provide capital, specialized technology and markets in order to accomplish its goals, one of which is to reach 4 MMBD of production by the end of the century.
Financial Outlook for the Canadian Gas Industry
Authors: Friedenberg Brent
Published: July 2017

The financial outlook for the Canadian gas industry depends on the outlook for gas prices at Canadian producing basins, the cost of producing in Canada and the volume of production of Canadian natural gas. Price, cost and volume determine the health of the Canadian industry. Industry's costs are the basis of the supply (volume) offered on the market and price is determined by the interaction of supply and demand.
The Effect of Financial Interpretation No. 46 on Electric Utility Companies
Authors: Pourjalali Hamid , Wilde Lauren T. F. , Clarke Robert F.
Published: July 2017

The objective of this research was to define and empirically test the effect of Financial Interpretation No. 46 (FIN 46) on electric utility companies. FIN 46 requires that Variable Interest Entities be reviewed and their financial information be consolidated in their primary beneficiary financial statements. When FIN 46 was issued, the electric utility companies expected that, in consolidated statements, their liabilities would increase to the degree that the result would be an increase in their cost of capital. Therefore, we expected that the implementation of FIN 46 would result in an increase in the cost of obtaining capital in electric utility companies. The results did not support this supposition. We found no significant changes in the cost of capital (when measured by changes in companies' bond rating) that could be associated with additional consolidation resulting from FIN 46. The two tests used in this study (T-test and Probit analysis) did not provide significant evidence that companies affected by FIN 46 were different from those that were not affected. We did find, however, that electric companies that were smaller and reported lower debt were affected by the FIN 46 requirement more than their larger counterparts. Some results suggest that the complete effect of FIN 46 is yet to be included in some of the electric utility companies' statements. Not considering the possible influence of such future effects, however, our results suggest that FIN 46 has not had a significant and costly effect on the electric utility companies.
Management of Otolaryngic Patients Susceptible to Malignant Hyperthermia Without Dantrolene
Authors: Derkay Craig S. , Grundfast Kenneth M.
Published: July 2017

Malignant hyperthermia (MH) is an adverse reaction most frequently associated with the administration of halogenated inhalational anesthetic agents and the depolarizing muscle relaxant succinylcholine. Characteristic findings are a hypermetabolic state accompanied by extreme hyperpyrexia, acidosis, rhabdomyolysis, and generalized muscle rigidity, often involving the masseter muscles. Dantrolene sodium, which was approved in 1979 by the FDA for use in the prevention of MH in high‐risk patients, has neurologic and gastrointestinal side effects. At the Children's National Medical Center (CNMC), 24 children identified as being at risk for the development of a MH reaction were anesthetized for otolaryngic procedures by using “non‐triggering” anesthetics and without use of dantrolene sodium. These patients represent 56% of all patients at risk for MH or masseter muscle rigidity (MMR) reactions during an 8‐year period at the CNMC. There were no complications. Concomitant muscle biopsies were performed, and caffeine/halothane contracture studies were completed in 18 of these patients, demonstrting 11 susceptible or equivocal responses. The data suggest that children undergoing common otolaryngic procedures who are at risk for development of MH may be safely anesthetized without the use of prophylactic dantrolene sodium.
Increased Nasal Eosinophils in Children with Otitis Media with Effusion
Authors: Caffarelli Carlo , Cavagni Giovanni , Giordano Salvatore , Savini Enrico , Piacentini Giorgio
Published: July 2017

The pathogenesis of otitis media with effusion is still under debate, but allergic sensitization has been suggested in some cases. We investigated whether nasal cytology may indicate an allergic pathogenesis for otitis media with effusion. Atopic symptoms, results of skin prick tests to common aeroallergens, and nasal cytology by nasal scraping were evaluated in 40 children with current otitis media with effusion and compared with findings in a group of 40 healthy children. The presence of nasal eosinophils was significantly more frequent in children with otitis media with effusion than in the control group (p < 0.05). Nasal eosinophils were significantly associated with both allergic rhinitis (p < 0.001) and positive skin prick test results (p < 0.001). Allergic rhinitis with nasal eosinophilla was found in six children of the study group and in one child of the control group (p < 0.05). Our data suggest that nasal allergic Inflammation may play a role in a subset of patients with otitis media with effusion. Therefore the possibility of allergic sensitization must always be considered in patients with serous otitis media.
A simple adsorption equation for adsorption of nonionic surfactants on hydrophilic surfaces of silica
Authors: Rudzinski W. , Dominko A. , Partyka S. , Brun B.
Published: July 2017

Using methods of statistical thermodynamics, simple equations were developed describing adsorption isotherms of non-ionic surfactants from water onto polar surfaces. Their derivation was based on some generally-accepted views on the adsorption mechanism in these systems. In particular, on the assumption that at increasing surfactant concentrations a change in the orientation of the primarily adsorbed molecules can take place. Effects of secondary adsorption are also taken into account. An extensive model investigation based on our simple equations yields all the types of experimental adsorption isotherms reported so far in literature. Equations were also tested against some more accurate experimental data, obtained recently in CNRS laboratory in Montpellier.
Preparation of active carbons from olive wood
Authors: LÓPez-Gonzlez J. De D. , Valenzuela-Calahorro C. , Navarrette-Guijosa A. , Gomez-Serrano V.
Published: July 2017

Active carbons were prepared by activating carbonized products (obtained by pyrolysis of olive wood in nitrogen at 1073 K) and olive wood itself under a flow of carbon dioxide at 1048 K. The effect on the development of surface area and porosity of such variables as activation time, heating rate, previous carbonization time, and starting material (either carbonized samples or wood) were followed by adsorption of nitrogen at 77 K. Changes of meso- and macroporosity during the activation process were monitored by mercury porosimetry. Surface area (BET values) varies from 469 up to 854 m2.g–1. A development of micro, meso and macroporosity takes place depending on activation time.
Non-Specific and Specific Interactions of Hydrocarbons with the Surface of a Non-Swelling Organo-Substituted Layer Silicate
Authors: Tarasevich Yu.I. , Bondarenko S.V. , Shulepov Yu.V. , Aksenenko E.V.
Published: July 2017

A molecular statistical method has been used to describe both specific and non-specific sorption of hydrocarbons on the surface of a non-swelling layer silicate (kaolinite) modified with octadecylammonium chloride. Sorption of n-hexane on this surface appears to be determined primarily by dispersion attraction to the modified overlayer, while specific interaction has been shown to play a major role in the case of benzene sorption. The energy characteristics of the benzene—RNH3+ adsorption complex have been estimated and the assumption that the benzene molecule is partially delocalized on the modified kaolinite surface shown to be reasonable.
The Mechanism of Alkali Metal Ion Sorption by Iron(III) Phosphate
Authors: Mustafa S. , Naeem A. , Nisa S.U. , Murtaza S. , Khalid M.
Published: July 2017

Alkali metal ion exchange (Li+, Na+ and K+) on iron(III) phosphate (FePO4) was studied potentiometrically as a function of temperature and metal ion concentration. The uptake behaviour of iron(III) phosphate was inferred from a comparison of the K+ ions sorbed and the loss of H+ ions from the exchanger. FT-IR spectroscopic studies and dissolution studies of FePO4 confirmed the uptake mechanism of alkali metal cations as cation exchange. The potentiometric titration data were employed to evaluate the apparent dissociation constants of iron(III) phosphate which were found to depend on the temperature of the system. The corresponding thermodynamic parameters ΔH0 and ΔS0 were also evaluated.
Static Adsorption, by Activated Carbons, of Vapour Mixtures Corresponding to Immiscible Liquids
Authors: Wintgens D. , Lavanchy A. , Stoeckli F.
Published: July 2017

It is shown that the static adsorption of benzene and water vapours by a typical industrial active carbon can be described by the model of independent co-adsorption proposed for compounds which are not miscible in the liquid state. The model assumes that the vapours are adsorbed according to their respective DA isotherms, each component using the micropore volume left unoccupied by the other. A good agreement is found between the calculated and the experimental adsorption, but in the case of water the model must take into account the decrease of the characteristic energy E(H2O) with increasing co-adsorption of benzene. This behaviour is confirmed by earlier studies of water adsorption and of immersion calorimetry into water, following variable pre-adsorption of n-nonane.
The Blacksburg Manifesto and the Postmodern Debate: Public Administration in a Time Without a Name
Authors: Marshall Gary S. , White Orion F.
Published: July 2017

The question, “Does the message of the Blacksburg Manifesto fit the times that we are in now and the times that seem to be shaping up in the next decade or longer?” is addressed by epistemologically locating the Blacksburg Manifesto and by introducing the postmodern debate to the field of public administration. The well-known Blacksburg Manifesto is described as an example of high modernism, beyond the functionalist paradigm, because although the central commitment is to reason and progress, the classic forms of administrative rationality are surpassed. It is classified as high modernism because the agency perspective, as articulated in the Manifesto, calls for a dialogue that evokes reason through process in the tradition of Mary Parker Follett. The postmodern experience is described as connoting a world of immense complexity, hyperdiversity, and self-referentiality. Postmodernism requires assuming a posture toward the world that tolerates fundamental ambiguity and paradox. A postmodern perspective on the Blacksburg Manifesto is presented and the central paradox of the Manifesto is exposed.
Theory of Strategic Action for Public Policy
Authors: Skok James E.
Published: July 2017

Strategic scenarios, concepts that assist business managers in developing market interventions, represent the action component of strategic management. In some fields of public policy (especially national defense and electoral politics) scenarios have been discussed for years. For the most part, however, a theory of action involving specific scenarios has not been given attention by scholars of public policy and administration. In this article, the literature of these fields, along with that of business strategy, is reviewed and synthesized for the purpose of beginning the process of developing a theory of action for managers of public policy. Two concepts in particular—the agency power matrix and the change scenario—are presented as necessary components of this theory. When completed, the theory of strategic action should be viewed as an integral part of the literature of strategic management.
An Investigation of Leadership Skill Differences in Chief Executives of Nonprofit Organizations
Authors: Herman Robert D. , Heimovics Richard D.
Published: July 2017

The increasing recognition of the public nature of nonprofit organizations and the changing relationships between governments and nonprofit organizations provide the context for, and underline the importance of, understanding effective executive leadership in such organizations. A study of 50 nonprofit organization chief executives revealed that reputationally effective executives engaged in more reported leadership behaviors in relationship to their boards of directors than executives not so reputed. No difference was found in reported leadership behaviors directed at staff. The results suggest that “board-regarding behaviors” are an important and distinct cluster of skills for effective leadership by nonprofit chief executives. The results are consistent with a resource-dependence perspective, and the authors argue that effective executives work with and through their boards in order to affect the constraints and dependencies in the nonprofit organization's environment.
Trauma Exposure and Posttraumatic Stress Disorder in the Canadian Military
Authors: Brunet Alain , Monson Eva , Liu Aihua , Fikretoglu Deniz
Published: July 2017

Objective:

To estimate the lifetime prevalence of trauma exposure and posttraumatic stress disorder (PTSD) among a representative, active military sample, and to identify demographic and military variables that modulate rates of trauma exposure as well as PTSD rates and duration.

Method:

A cross-sectional weighted sample of 5155 regular members and 3957 reservists ( n = 8441) of the Canadian Armed Forces (CAF) was face-to-face interviewed using a lay-administered structured interview that generates Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, psychiatric diagnoses.

Results:

Within this sample, 85.6% reported 1 or more trauma exposure, with a median number of 3 or more exposures. Compared with males, females were less likely ( P < 0.05) to be exposed to warlike trauma (adjusted odds ratio [AOR] 0.40), disasters (AOR 0.43), assaultive violence (AOR 0.52), and witnessing trauma (AOR 0.75). However, they were more likely to report sexual assault (AOR 7.36). The lifetime prevalence of PTSD was 6.6% and the conditional rate was 7.7%. Both lifetime and conditional PTSD rates were higher among female soldiers, but lower among the reserve forces, both male and female. Finally, the median duration of PTSD was negatively influenced by younger age of onset, but not influenced by whether the event occurred during deployment.

Conclusions:

Active members of the CAF report a high degree of trauma exposure but a moderate rate of lifetime PTSD.
Residence Conditions on Community Treatment Orders
Authors: Dawson John , O'Reilly Richard
Published: July 2017

Objective:

To identify the clinical reasons and legal authority for including a residential placement condition in a community treatment order (CTO).

Method:

We describe the clinical reasons for imposing a residence condition and discuss how this is authorized by the laws of the Canadian provinces (using Ontario as the main example).

Results:

A residence condition can facilitate numerous benefits, including: regular access to a person by a clinical team; continuing therapeutic relations; supervision of medication; provision of general medical care; and reduction in substance use, risks of victimization, and other unintended harm. A resident condition can be lawfully imposed when it clearly fits the purposes of the CTO legislation and stops short of authorizing detention in a community facility.

Conclusions:

In certain circumstances, a residence condition is clinically justified and a lawful aspect of a CTO.
The Influence of Velocity in Low-Velocity Impact Testing of Composites Using the Drop Weight Impact Tower
Authors: Rydin R. W. , Bushman M. B. , Karbhari V. M.
Published: July 2017

Many structural advantages offered by composites due to their inherent tailorability await realization for lack of a clear understanding of their response under transient loading. One tool currently available for evaluation of impact response is the drop weight impact tower. In this paper, we address the influence of impact velocity in drop tower testing using woven and non-woven E-glass fabric-reinforced vinyl-ester composites fabricated by resin transfer molding (RTM). For the range of impact velocities attainable in a typical drop weight impact tower (< 7 m/s), impact energy and contact force determine the extent and type of damage. Impact velocity determines the initial loading slope and time taken to reach maximum load; however, it only marginally influences inelastic damage accumulation. Peak contact force increases linearly with impact energy and projected damage area up to the linear inelastic limit (LIL), which is described as the point where top surface penetration commences. While independent of impact velocity, LIL marks the upper limit of applicability for the well-known linear relationship between projected damage area and impact energy. Beyond LIL, these two composite systems offered no increased resistance to load application, suggesting that ultimate contact force may be an important impact metric.
Test Methods for FRP-Concrete Systems Subjected to Mechanical Loads: State of the Art Review
Authors: Nanni A. , Bakis C. E. , Boothby T. E.
Published: July 2017

This report addresses the methodology for determining the long-term behavior of bridge structures reinforced with fiber reinforced plastic (FRP) rods. In particular, a review of the existing literature on what has been done and what needs to be done for the development of accelerated test methods, with emphasis on mechanical loads, is presented. The focus of the report is on new, bonded FRP reinforcement for concrete bridge structures. Companion reports address stand-alone FRP systems subjected to mechanical loads, and stand-alone FRP and FRP-concrete systems subjected to environmental loads.
Accelerated Test Methods to Determine the Long-Term Behavior of FRP Composite Structures: Environmental Effects
Authors: Bank Lawrence C. , Gentry T. Russell , Barkatt Aaron
Published: July 2017

Technical literature on the subject of environmental exposure effects related to determining accelerated test methods for the prediction of long-term performance of FRP composite materials for highway structural applications is reviewed in this paper. Effects of environmental exposure of a chemical and a thermal nature on fiberreinforced polymer (FRP) composites are considered. Such exposures include temperature, moisture and chemicals in liquid solutions or in gaseous mixtures. The effects include the changes in the physical and mechanical properties of the composite materials. Such changes are typically related to the degradation or deterioration of the composite material. Synergistic effects of mechanical load and exposure are also reviewed. The review is divided in topics entitled Materials, Exposure Conditions, Experimental Techniques, Failure Mechanisms and Theoretical Modeling.
Connection and Reinforcement Design Details for Pultruded Fiber Reinforced Plastic (PFRP) Composite Structures
Authors: Mosallam Ayman S.
Published: July 2017

This paper aims at introducing some suggested design detail recommendations for connections and stiffeners for pultruded fiber reinforced plastics (PFRP) structural shapes. It also serves as a practical design reference for PFRP fabricators in selecting the appropriate connection configurations. The anisotropic nature of the material has been considered in preparing these structural details. This paper is divided into three interrelated parts: 1) connection design details for PFRP frame structures; 2) simplified stiffening details to reinforce and increase the structural capacity of PFRP open-web profiles; and 3) experimental evaluation of stiffened PFRP beams. In the first part, connections for new construction using customized FRP Universal Connectors (UC), developed by the author, are presented along with the required stiffeners to minimize the localized deformation and to overcome the premature failure of PFRP open-web profiles. This common localized failure PFRP open-web profiles was reported earlier in several papers by the author and others. In addition, shear and flexural stifrening details are presented. To solve the problems associated with existing PFRP frame structures, suggested details for transfer elements and stud stiffeners are also presented. These additional stiffening details to existing PFRP structures are not costly, and will assist in increasing both the reliability and safety of such structures under excessive loading conditions. Consequently, this will reduce the risk and the liability imposed on both the designers and the fabricators. In addition, experimental results of both stiffened and unstiffened simply supported PFRP H- beams are presented to demonstrate the importance of using additional stiffeners to off-theshelf pultruded profiles. The result of this experiment indicates that an increase up to 65% of the ultimate loading capacity of the section can be achieved compared to unstiffened specimens. In addition, an increase in both critical buckling stress and post-buckling strength was the result of adding these stiffeners.
Elastic/Viscoplastic Behavior of Fiber-Reinforced Thermoplastic Composites
Authors: Wang C. , Sun C. T. , Gates T. S.
Published: July 2017

An elastic/viscoplastic constitutive model was used to characterize the nonlinear and rate dependent behavior of a continuous fiber-reinforced thermoplastic composite. This model was incorporated into a finite element program for analysis of laminated plates and shells. Details on the finite element formulation with the proposed constitutive model were presented. The numerical results were compared with experimental data for uniaxial tension and three-point bending tests of [± 45013, APC-2 lamintes.
Compressive Failure Due to Shear Instability: Experimental Investigation of Waviness and Correlation with Analysis
Authors: Wisnom Michael R. , Atkinson James W.
Published: July 2017

Tv1 panels of unidirectional T800/924 carbon fibre-epoxy were fabricated with a kink running across the width to produce fibre waviness. One panel had maximum fibre misalignment varying through the thickness from about 1.70 to 3.9° with a wavelength of about 6.0 mm, and the other varied from 2.20 to 5.60 with a wavelength of about 6.6 mm. Specimens loaded in compression showed increasing bending followed by catastrophic failure at average stresses of 1085 and 840 MPa. This is well below the compressive strength of 1816 MPa reported elsewhere for nominally straight specimens, confirming the critical effect of fibre waviness. The stress-strain response of the specimens was predicted well from finite element analysis accounting for large fibre rotations and non-linear shear properties. Failure was predicted at stresses 5.6% and 8.0% below the measured values. The model showed that the failure was precipitated by shear instability rather than classical compressive instability. The good correlation obtained validates the modelling approach and shows that it can be applied to predicting the effects of fibre waviness in composite components.
The Influence of Water Immersion on Skin-Core Debonding in GFRP-Balsa Sandwich Structures
Authors: Cantwell W. J. , Broster G. , Davies P.
Published: July 2017

A new test technique has been developed in order to characterise the skincore interfacial properties of a series of fibre reinforced sandwich structures similar to those presently being used in the marine industry. The technique involves peeling the lower surface skin away from the core in a controlled fashion. Four different glass fibre reinforced epoxy/balsa structures have been tested and the effect of incorporating various skin-core interlayers assessed. Tests were also undertaken on specimens that had been immersed in seawater for a period of forty-five days.

The results indicate that the fracture energies associated with skin-core debonding are relatively high, typically 1000 J/m2. It has also been shown that neither a pre-treatment of the balsa core nor the incorporation of a layer of CSM fibres resulted in an improvement in the fracture energy of the interfacial region. Immersion in seawater for forty-five days resulted in a significant increase in the fracture toughness of this region. A subsequent examination of the fracture surfaces showed that fibre bridging between the GFRP skin and the balsa core was more extensive in the soaked samples.
Design and Manufacturing of Filament Wound Elastomeric Matrix Composite Flywheels
Authors: Gabrys C. W. , Bakis C. E.
Published: July 2017

A procedure for the filament winding of thick glass and carbon fiber reinforced urethane matrix composite flywheels is presented. The impetus for fabrication of urethane matrix composite rings, which is discussed in the paper, stems from several potential advantages they may offer in high speed flywheels over conventional rigid epoxy matrix rings. The method developed uses continuous in-situ curing of the part while it is being wound to avoid compositional variations throughout the thickness, to eliminate fiber waviness and also to allow very high speed manufacturing. Urethanes typically have extremely high room-temperature viscosities and very short elevated temperature pot lives which combine to make conventional fiber impregnation schemes difficult. A method of diluting the resin with a solvent was developed in order to lower the viscosity. This method allows good room temperature fiber impregnation while avoiding the waste generated with continuous resin mixing systems for elevated temperature impregnation. After impregnation, heaters flash the solvent from the tow prior to being wound into the part. Results show that high quality parts with high fiber content (about 60%) and low void content (less than 1%) can be easily fabricated at radial deposition rates as high as 3.23 cm/hr (1.Z7 in/hr).
Loading Rate Effect on Mode I Interlaminar Fracture of Carbon/Epoxy Composite
Authors: You Hee , Yum Young-Jin
Published: July 2017

Fracture testing was performed for the Carbon/Epoxy double cantilever beam specimens to investigate the effect of loading rate on the interlaminar fracture toughness of composite laminate. Fracture toughness was obtained from the relationship of displacement and crack length. It showed little change up to 2 mm/sec of loading rate, however, 44% increase was observed at 20 mm/sec and 73% increase at 120 mm/sec. Critical crack propagation speed was found to be between 6 mm/sec and 14 mm/sec from the change of fracture toughness for crack propagation speed which divides static loading range and high rate range.
Design of a Cylindrical Specimen for Biaxial Testing of Composite Materials
Authors: Smith L. V. , Swanson S. R.
Published: July 2017

The design and analysis results of a specimen and fixture to study the failure of composite materials under biaxial loading environments are presented. The objective of the current study was to achieve a capability of transmitting higher axial loads than had been achieved previously. The magnitude of the axial load is limited by failure and debonding of the end-tab which is bonded to the composite. Higher axial loads were achieved primarily by designing an end-tab geometry to put the bondline normal stress in compression, which was found to increase the bond shear strength, and by careful material selection for the end grip region. The end-tab was analyzed using finite elements to verify a smooth introduction of load in both the axial and hoop directions. Experiments showed that the grip and apparatus design was successful in achieving gage section failures over a wide range of biaxial test conditions. Biaxial test results are presented for tension-tension and compression-compression tests of carbon/epoxy braid specimens to illustrate the present test methods.
Numerical Study on the Capillary Effect of Resin Transfer Molding
Authors: Chang Chih-Yuan , Hourng Lih-Wu , Wu Ching-Jenn
Published: July 2017

A model for the impregnation of resin into a unidirectional packed fiber mats by the dynamics of capillary penetration is developed at a low flow rate where resin flow is parallel to fiber axis. The model takes into account two types of flow, the macroflow around the fiber bundles and the microflow around the fibers in the bundles, occurring simultaneously. Both follows are described by Darcy's law. The large difference in the position of flow front between these two types of flow leads to the potential of void formation in resin transfer molding. The capillary force is considered along the flow front. It can be evaluated as a function of liquid contact angle, interfacial tension, the porosity, and the velocity of flow front. The simulation is based on the body-fitted finite element method. Result shows that the void formation is affected not only by the properties of fiber mats, but also by the injection condition. And the capillary effect is limited as the capillary number is less than 0(10-2).
Influence of Joint Geometry and Load Regimes on Sandwich Tee Joint Behaviour
Authors: Shenoi R. A. , Read P. J. C. L. , Jackson C. L.
Published: July 2017

Fibre reinforced plastic (FRP) sandwich construction incorporating PVC foam cores is becoming an increasingly used structural topology in the case of ships, boats and offshore structures. A critical part in such structures is the connection between two orthogonal plate assemblies such as bulkheads and shell plating. This is usually in the form of a laminated teejoint. The purpose of this paper is to characterise the behaviour of such connections in terms of key stress components in the various constituent elements of the tee. This is done in context of various joint geometries and loading regimes. It has been shown that the collated results can be presented in the form of regression equations which are functions of geometry and which can then be used for design synthesis purposes.
3-D Technology in Blow Moulding: A Numerical Simulation
Authors: Debbaut Benoît , Marchal Thierry
Published: July 2017

A numerical simulation is presented for the analysis of 3-D technology in blow moulding process. The fluid parison is described by means of a membrane element whilst a Lagrangian formulation is used for the governing equations. The numerical algorithm is applied to the case of a bent, three-dimensionally shaped tube. The contact between the guided parison and moving mould parts is handled by a robust technique. Next to the description of the parison motion, we concentrate on the prediction of wall thickness and extension components evaluated in both machineand cross-directions.
Toughness of Long Glass Fiber Reinforced Thermoplastics
Authors: Glenn Lee W. , Kim Hong C. , Miller Daria E. , Ellis Chris S.
Published: July 2017

The toughness properties of long glass fiber reinforced thermoplastics were characterized using different testing modes including tensile, pendulum type impact, falling weight impact, and fracture toughness tests. The effects of glass fiber length, resin type, temperature, and testing mode on the toughness properties of reinforced thermoplastics were also studied. It was found that a longer glass fiber length and nylon 6/6 matrix lead to higher toughness properties. The effect of long glass fibers was most prominent in Izod impact properties. The reduction of toughness at-40'C compared with room temperature was much less for the long glass fiber reinforced thermoplastics.
The Effect of Surface Treatment on Mechanical Properties of Injection Molded Composites
Authors: Tanaka T. , Waki Y. , Hamamoto A. , Nogami N.
Published: July 2017

The filler treated with silane and polysiloxane is compounded in polymer matrix. After injection molding of these compounded materials, the mechanical properties were evaluated, especially IZOD IMPACT strength. In order to make filler-polymer compounds, a twin screw extruder has to be used. The filler treated with polysiloxane can be dispersed in polymer matrix as much smaller particle size than treated with silane. This means that the IZOD IMPACT strength of the filler treated with polysiloxane is better than that treated with silane.
Flow Directions in the Gas Assisted Injection Molding Technology
Authors: Soh Young Soo , Chung Chan Hong
Published: July 2017

A method is introduced to predict the preferred direction of gas in gas assisted injection molding processes. The method requires a knowledge of the relations between resistance for the gas flow and 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.
Effect of Various Polyethylene Structures on Film Extrusion
Authors: Wong C. M. , Shih H. H. , Huang C. J.
Published: July 2017

Viscoelastic behaviors and film extrusion are concerned in this study. Several materials are tested. They are a low density polyethylene, a linear low density polyethylene, and two metallocene polyethylenes. Molecular weight, molecular weight distribution, storage modulus, and loss modulus have been measured to interpret the viscoelastic behaviors. The energy consumption and output rates are described at various screw revolutions. A wide range of drawdown ratios, blowup ratios with frost-line heights in film blowing is investigated in order to determine the region of bubble stability.
Experimental Analysis of Core Crushing and Core Movementin RTM and SRIM Foam Cored Composite Parts
Authors: Wirth Stephane , Gauvin Raymond , Kendall Ken
Published: July 2017

In liquid composite molding, SRIM can typically achieve a higher pressure than the RTM process. When molding a foam cored composite part at high flow rates using an SRIM system, the following related effects can be observed: high molding pressures, core shifting, core crushing, variable permeability and reinforcement compaction. Because of the variable permeability in such conditions, the linear Darcy law does not apply for flow simulation. Finally, all this can easily result in dry spot defects.

To study the various problems occurring in the molding of foam cored composite parts, two molds equipped with pressure transducers were used. The first one was a picture frame square plaque mold. To ease the measurement of reinforcement compaction and core crushing, flat panels were molded with reinforcement on one side only. The second part was a quasi-rectangular foam cored beam with braided reinforcement all around the foam core. In this paper, it is refered as the Small Core part. With this part, reinforcement compaction, core crushing and core shifting was measured.

The picture frame plaque mold was used with the RTM and SRIM processing equipment. Continuous strand mat with a constant fiber volume fraction was used with polyurethane foam of variable density. For the RTM process, Vinyl Ester resin was injected at constant pressure while for SRIM, Polyurethane resin was injected at constant flow rate. Parts were cut to measure laminate thickness and core deformation. For the Small Core mold, only the SRIM system was used with a constant flow rate. In this case the core materials used were Polyurethane of various densities. All parts were braided with ±45 and axial (0°) glass filaments. For some parts, locators were placed on the core surface to prevent its shifting. Short shots were used to observe the resin flow progression.

For the picture frame experiments, the RTM process gave no significant core deformation. With the SRIM system, results showed a non-negligible core deformation at some foam densities. The SRIM system was also used with the Small Core tool. The results revealed the dominance of the core shifting and fabric compaction over core crushing. The use of locators placed on the core surface led to a better flow progression and nearly eliminated the core shifting, resulting in a part without defects. The flow simulation software RTMFLOT developed in our laboratory and based on a linear Darcy Law was used with these complex cases. The simulation results gave a good approximation of the gate pressure during filling.
Interlaminar Strains and Compressive Strength Reductions Due to Nested Layer Waviness in Composite Laminates
Authors: Bradley Douglas J. , Adams Daniel O. , Gascoigne Harold E.
Published: July 2017

Layer waviness, or out-of-plane layer undulations in a composite laminate, has been shown to produce significant reductions in compressive strength. The object of this research was to directly correlate experimentally determined strain fields and compressive strengths with analytical predictions. Two layer wave formations were intentionally fabricated into otherwise wave-free carbon/epoxy cross-ply laminates: a single wavy layer and three nested wavy layers. Moire interferometry, mechanical testing, and finite element analysis were used to determine interlaminar strains and compressive strengths. Results indicate that under compression loading, large interlaminar shear and normal strains, comparable to the magnitude of the applied strain, occur as a result of layer waviness. Experimentally, the three nested layer wave formation produced a significantly larger strength reduction than the single layer wave. Using the maximum stress as well as the Hashin failure criteria, however, only a slight additional reduction in compressive strength was predicted for the three nested layer wave case as compared to the single layer wave. These results suggest that although the finite element model properly predicts deformations and interlaminate strains associated with layer waviness, simple stress-based failure criteria are not adequate for predicting compressive strength reductions associated with naturally occurring formations of layer waviness.
Formation and Characterization of Cast, Tubular and Biaxially Stretched Poly(butylene Terephthalate) Film
Authors: Song Kwangjin , White James L.
Published: July 2017

An experimental study of structure development in cast film, single bubble tubular film extrusion and double bubble tubular film extrusion of polybutylene terephthalate is described. We also study the characteristics of biaxially stretched PBT films. Cast and single bubble film exhibited only α-form crystallite and relatively low crystallinity (Xc = 18-22%), while double bubble and biaxially stretched cast films showed a mixed character of both α-andβ-form crystallites with crystallinity (Xc = 20-30%). WAXS pole figures indicate that polymer chains orient rapidly with uniaxial stretching. Biaxiality of orientation increases with simultaneous transverse stretching. The phenyl rings become aligned parallel to the film plane with biaxial stretching. The level of orientation is substantially higher in both double bubble and biaxially stretched cast films than in single bubble films. Annealing further increases crystallinity and orientation of the films.
Pressure Generation and Screw Design in Corotating Twin Screw Extruders
Authors: Huneault Michel A.
Published: July 2017

In order to properly design the screws and to locate feed and devolatilization ports, it is necessary to determine the extent of filled zones and to evaluate the pumping and mixing efficiency of different kneading sections. This paper presents an experimental study of the pumping efficiency of forward and backward pumping screws and kneading sections. Results indicate that the pumping efficiency is generally greater than that predicted by 2D inelastic models and that left-handed elements do not necessarily fill entirely, especially at their downstream end where backward pumping and forward pumping flights meet.
Analysis and Modeling of the Residence Time Distribution in Intermeshing Co-rotating Twin Screw Extruders Based on Finite Element Simulations
Authors: Potente H. , Flecke J.
Published: July 2017

In the field of compounding and reactive extrusion the residence time distribution, among other factors, represents an important factor for the evaluation of the process behavior in co-rotating twin screw extruders. The corresponding literature presents us with a lot of publications regarding this subject. Mostly, these are empirical approaches to describe the residence time behavior or more experimental analyses. The existing description forms are often taken from the single-screw theory and are applied to the twin screw extruder.

This paper is meant to present a new analysis and description of the residence time behavior of a co-rotating twin screw extruder which is based on 3-D finite element simulation for power law fluids. The residence time is thus determined and evaluated by means of streamlines taken from flow simulation. As a result the existing description formulations compared with experimental data for the operating parameters needed in practice are mostly out of the extent of validity. This is due to the high speed with a pre-defined melt throughput and the exceptional channel geometry of the tightly intermeshing co-rotating twin screw extruder.
Experimental Study of Extruding Behavior against Material Property in the Filler Mixing by Intermeshing Co-Rotating Twin Screw Extruder (II)
Authors: Ishibashi J. , Kobayashi A. , Yoshikawa T.
Published: July 2017

Plastics mixed with mineral fillers are extensively used in various fields. Co-rotating twin screw extruder are generally used as a compounder for mixing plastics with filler. In ANTEC '96, we presented the study about the feeding system which supplies resin and filler together in the filler compounding by co-rotating twin screw extruder (hereinafter TSE) [1].

The present study investigated extruding behavior in the side-feeding system of filler compounding by TSE. This study verified by experiment how the MFR of polypropylene (hereinafter PP), the particle size and the mixing ratio of talc influence on the extruding capacity. Results of experiment indicated that the higher mixing ratio and the smaller particle size of talc made throughput rate lower. On the other hand, difference in the MFR of PP was found to have a little influence. Amount of the air contained in the talc was found to have great influence on the throughput rate.
Pressure Drop of the Polymer Melt Flow in a Pipe
Authors: Ling Fuhua
Published: July 2017

Rheological properties of polymer melts are often described with a linear model, the two-parameter power-law model in industrial applications, while the real polymer melts behave more or less nonlinearly, particularly in the low shear rate regions. In a lot of real flows, such as the simple pipe flow, there is even a zero shear rate region. Therefore, the adequacy of this linear approximation has to be examined. In this paper, the polymer melt flow in a pipe is studied using the nonlinear three-parameter Powell model. Numerical results are presented in several graphs, which can be used in engineering calculations. A comparison with the test data has been given. The restrictions of using the power-law model and the impact in handling the experimental data are discussed.
Acoustic Emission from CFRP Laminates during Fatigue Loading
Authors: Tsamtsakis D. , Wevers M. , de Meester P.
Published: July 2017

The fatigue behaviour of quasi-isotropic carbon fibre reinforced epoxy laminates under tension-tension cyclic loading is investigated. The acoustic emission technique is used to monitor the different damage mechanisms activated throughout the fatigue life. Filtering of acoustic emission events is performed to reject the events attributed to friction related mechanisms. After appropriate filtering of the AE data, the fatigue damage process can be monitored in terms of cumulative AE counts.
Analysis of the Relationship between Processing Conditions-Fiber Orientation-Final Properties in Short Fiber Reinforced Polypropylene
Authors: Barbosa Silvia E. , Kenny Jose M.
Published: July 2017

Within the general objective of analyzing and modeling the processability of polypropylene and of its short fiber composites, a comprehensive analysis of the relationship between processing conditions, fiber orientation distribution and final properties has been performed. This relationship was analyzed for injection molded plates and studied as a function of the position in the plate. Final properties analyzed were impact strength, and flexural and elasticity modulus. In all the samples tested an accurate analysis of the fiber orientation distribution was performed and the results were related to the mechanical properties measured. The complex relationship between processing conditions, fiber distribution and mechanical behavior has been described by statistical correlations. This approach represents a useful alternative to the modeling route to predict the processing behavior of semicrystalline polymers and of their composites.
On the Use of Darcy Permeability in Sheared Fabrics
Authors: Dungan F. D. , Senoguz M. T. , Sastry A. M. , Faillaci D. A.
Published: July 2017

Determination of a set of processing parameters for a given material type is a complex process, and much work has been done using the framework developed in the last century by Darcy. While this model, assuming Newtonian flow through a granular (essentially a smoothed, porous) medium, has produced useful flow front progression simulation tools, a commonly arising problem in the fabrication of complex components is the modeling of flow front through regions of locally high shear. Several current approaches stem from a modification of the Darcy description using "local" permeabilities for these regions, differing from the permeabilities experimentally obtained in the unsheared or undeformed state. The work presented here investigates the applicability of a transformation of the permeability in the unsheared state, and conjectures that the driving forces for the fluid flow may be sufficiently complex to merit more detailed constitutive modeling in complex fabric architectures. Experiments on sheared fabrics have been performed, and permeabilities are compared with those obtained by tensor-transformation of unsheared fabric permeabilities.
Brain Abnormalities in Tuberous Sclerosis Complex
Authors: DiMario Francis J.
Published: July 2017

Tuberous sclerosis complex is an autosomal dominant multisystem disorder. Spontaneous mutations occur in up to 60% of patients with gene loci located on chromosomes 9q34 ( TSC1) and 16p13 ( TSC2). Diagnosis is established with the identification of various neurocutaneous markers and multiple organ system hamartomas. The variable expression of severity, the potential for cognitive dysfunction, and epilepsy compound the clinical picture. The intracranial abnormalities include the identification of migration and hamartomatous brain lesions, such as tubers, subependymal nodules, and subependymal giant cell astrocytomas. A number of other neuroimaging and morphometric abnormalities coexist, which can be identified with current neuroimaging techniques. This review examines the spectrum of brain abnormalities encountered in tuberous sclerosis complex and presents them as not merely a collection of lesions but more cohesively in the context of a global neuronal migration disorder. ( J Child Neurol 2004;19:650—657).