Rethinking Enterprise Architecture for Sustainable Energy System Development

The development of a sustainable energy system throughout an enterprise is a complex task, which requires an agile holistic approach. Such an approach needs to include a variety of objectives including energy strategy formation and strategic decision-making, which are directly related to the analysis and management of the main areas of sustainable development:The economic, technological, environmental, and social. These multidimensional requirements of sustainability are often difficult to achieve within the enterprise, because these aspects are interrelated and influenced by various internal and external environment factors. This paper first reviews the main challenges for an energy system, and then demonstrates how a strategic agile enterprise architecture driven approach could effectively guide the sustainable energy system development. The study presented in this paper provides a holistic approach that contributes to the advancement and usage of literature dealing with issues of sustainable energy system development and agile enterprise architecture, which has not been discussed before to any great extent.     

The effect of cooling rate on the impact performance and dynamic mechanical properties of rotationally molded metallocene catalyzed linear low density polyethylene

This article examines changes to the morphology of rotationally molded metallocene catalyzed linear low density polyethylene brought about by varying the cooling rate during processing. These changes in morphology lead to variations in the impact performance, which is reflected in the dynamic mechanical characteristics of the materials. Various analytical techniques are used in an attempt to explain the differences in impact behavior. Slow cooling is shown to result in high crystallinity, and in the formation of large spherulites, which in turn is detrimental to the impact performance of the material, particularly at low temperatures. The high crystallinity corresponds with a shift in the β transition of the material to a higher temperature, and is shown to result in a higher brittle–ductile transition. A case study was also carried out on samples from a finished part provided by an industrial molder, one section of which failed in a brittle manner when impact tested while the other failed in a ductile manner. Microscopy results showed that the brittle material had large spherulites at the inside surface, while the ductile material showed incipient degradation at this surface, which has previously been shown to be of benefit to impact strength in rotationally molded parts. Dynamic mechanical studies again showed a β transition at a higher temperature in the brittle samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1963–1971, 2006     

Relationship between crystalline structure and mechanical behavior in isotropic and oriented polyamide 6

Polyamide 6 (PA6) isotropic films and oriented cables were prepared by compression molding or by consecutive extrusion and cold‐drawing. These samples were isothermally annealed in the 120–200°C range and were then subjected to tensile tests at room temperature. Synchrotron wide‐angle X‐ray scattering (WAXS) and small‐angle X‐ray scattering (SAXS) patterns were obtained before and after mechanical failure. These data were related with the mechanical properties of the respective PA6 samples. The annealing of isotropic PA6 resulted in an increase in the Young's modulus (E) and yield stress (σ_y) values, which was attributed to the observed proportional reduction of the d‐spacings of the intersheet distances in both the α‐PA6 and γ‐PA6 polymorphs. Analysis of the WAXS and SAXS patterns of isotropic PA6 after break allowed the supposition of structural changes in the amorphous phase, with these being better pronounced with increasing annealing temperature; this made the samples less ductile. In oriented PA6 samples, annealing resulted in a drastic increase in the E and σ_y values accompanied by a phase transition from γ‐PA6 to α‐PA6 and a well‐pronounced reduction in the intersheet distances of both polymorphs. The stretching of the oriented samples led to an additional γ‐to‐α transition, whose extent was also related to structural changes in the amorphous phase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2242–2252, 2007     

Preparation,structural development,and mechanical properties of microfibrillar composite materials based on polyethylene/polyamide 6 oriented blends

The preparation of microfibrillar composites (MFCs) based on oriented blends of polyamide 6 (PA6) and high‐density polyethylene (HDPE) is described. By means of conventional processing techniques, the PA6 phase was transformed in situ into fibrils with diameters in the upper nanometer range embedded in an isotropic HDPE matrix. Three different composite materials were prepared through the variation of the HDPE/PA6 ratio with and without a compatibilizer: MFCs reinforced by long PA6 fibrils arranged as a unidirectional ply; MFCs containing middle‐length, randomly distributed reinforcing PA6 bristles; and a nonoriented PA6‐reinforced material in which the PA6 phase was globular. The evolution of the morphology in the reinforcing phase (e.g., its visible diameter, length, and aspect ratio) was followed during the various processing stages as a function of the blend composition by means of scanning electron microscopy. Synchrotron X‐ray scattering was used to characterize selected unidirectional ply composites. The presence of transcrystalline HDPE was demonstrated in the shell of the reinforcing PA6 fibrils of the final MFCs. The impact of the compatibilizer content on the average diameter and length of the fibrils was assessed. The influence of the reinforcing phase on the tensile strength and Young's modulus of the various composites was also evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Performance of North American Bioreactor Landfills. II: Chemical and Biological Characteristics

The objective of this research was to examine the performance of five North American bioreactor landfills. This paper represents the second of a two-part series and addresses biological and chemical aspects of bioreactor performance including gas production and management, and leachate chemistry. The data support accelerated methane generation at several landfills (k = 0.08–0.21?1/year) relative to the AP-42 default decay rate (k = 0.04?1/year). While the data indicate that gas collection increases at bioreactor landfills, a general relationship between decay rate and moisture added or wet weight water content could not be identified. There was no indication that gas collection increases appreciably when the water content reaches 40%. Most of the leachates at the landfills in this study were commingled from cells operating as a bioreactor and conventionally. Nevertheless, trends in pH and BOD:COD in the bioreactor leachates were consistent with the impacts of enhanced biological activity. Ammonia concentrations also increased over time but remained below levels reported to be inhibitory. For both heavy metals and speciated organic chemicals, there was no indication that bioreactor landfill leachate is significantly different from leachate generated at conventional landfills.     

Ammonia exchange on clinoptilolite from mineral deposits located in Mexico

This work investigated the ion exchange of ammonia on clinoptilolite obtained from mineral deposits located in San Luis Potosi and Sonora, Mexico. Experimental ion exchange isotherm data were obtained in a batch adsorber. The effects of temperature and solution pH on the ion exchange capacity were studied and it was found that the exchange capacity was slightly increased by augmenting the temperature and by decreasing the pH from 6 to 3. The ion exchange capacity was independent of the diameter of the zeolite particles. The reversibility of ion exchange was analyzed by desorbing the ammonia exchanged on the zeolite. The ion exchange was reversible when 1% NaCl solution was used as the desorbing solution, but more ammonia was desorbed using 1% KCl solution in the desorption step. It was concluded that a considerable amount of ammonia was exchanged on the clinoptilolite and that the exchange capacity was slightly dependent on the temperature and pH. Copyright © 2004 Society of Chemical Industry     

Microfibrillar composites based on polyamide/polyethylene blends. 1. Structure investigations in oriented and isotropic polyamide 6

The present paper discloses the structural changes caused by heating of polyamide 6 (PA6) samples with different thermal and mechanical histories in the 30-240 °C range. Wide and small-angle X-ray scattering (WAXS and SAXS) of synchrotron radiation, as well as solid-state nuclear magnetic resonance spectroscopy (NMR) measurements are performed. The NMR spectra show that in both isotropic and oriented samples there is a co-existence of α and γ-PA6 crystalline forms. Deconvolution of the WAXS patterns is performed to follow the temperature dependence of the unit cell parameters of the α and γ-forms and also of the equatorial (ECI) and total crystallinity indexes (CI), evaluating the contributions of the two crystalline phases. Estimates for the long spacing and for the average thicknesses of the crystalline (l_c) and amorphous (l_a) phases within the lamellae are calculated as a function of the heat treatment employing analysis of the linear correlation function calculated from the SAXS patterns. The X-ray results allowed the conclusion that upon heat treatment up to 160-200 °C, intensive transitions between the PA6 crystalline forms take place, whereby the content of the initial major crystalline phase decreases and that of the initial minor one increases reaching almost 1:1. Close to 200 °C a general trend toward increasing the content of the α-form is registered. The influence of annealing and quenching after melting on the PA6 crystalline structure is also studied.     

Relationship between the crystalline structure and mechanical behavior in isotropic and oriented polyamide 12

This study reports on the relationship between the crystalline structure and mechanical behavior of differently processed and annealed polyamide 12 (PA12) samples. Two sets of samples were obtained: isotropic PA12 films prepared by hot pressing and oriented cables prepared by consecutive extrusion and cold drawing. These samples were isothermally annealed in the range of 80–160°C and then subjected to tensile tests at room temperature. A combination of solid-state ¹³C-NMR and synchrotron wide- and small-angle X-ray scattering was used to obtain reliable structural data from these samples before and after the tensile tests. These structural data were related to the mechanical properties of the respective PA12 samples. Deformation models explaining all the experimental results were suggested for the different PA12 samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

ARGES: Radial segregation and helical instabilities in metal halide lamps studied under microgravity conditions in the International Space Station

HID lamps (High-Intensity Discharge) are gaining ground in the lighting industry because of their very high energy efficiency (up to 40%). In these lamps, which are operated in the arc regime and which are contained in a ceramic balloon, filled with argon or xenon, mercury, and salts of various rare earth metals and iodine), de-mixing occurs. This de-mixing is driven by differences in diffusion velocities of molecules and atoms. Furthermore, helical instabilities might occur in the lamp. Both phenomena are severely modified under 1 G conditions: convection will bend a horizontally burning arc channel upwards, and a vertically burning arc channel will exhibit convective cells. This makes it impossible to study these phenomena on the ground. If a proper understanding of these phenomena is to be gained, experiments under microgravity are necessary. The main objectives of the experiment are: (1) determination of the critical factors for the onset of helical instabilities in HID lamps and (2) characterisation of the radial de-mixing processes by radially resolved high-resolution emission spectroscopy. To this end, special hardware has been designed and built which houses a very compact high-resolution spectrometer, a video camera and a caroussel with 20 lamps in it. The lamps are measured consecutively. The experiments have been performed successfully by the Dutch astronaut André Kuipers on board the International Space Station during the Dutch Soyuz Mission “DELTA” on 24 and 25 April 2004. Especially the helical instabilities part yielded immediate and surprising results: the arc channel does bend, but does not rotate under microgravity. This fact is very important in improving the performance of the lamps, especially since the instabilities occur mainly in the most efficient lamps.