Kompics: a message-passing component model for building distributed systems

The Kompics component model and programming framework was designedto simplify the development of increasingly complex distributed systems. Systems built with Kompics leverage multi-core machines out of the box and they can be dynamically reconfigured to support hot software upgrades. A simulation framework enables deterministic debugging and reproducible performance evaluation of unmodified Kompics distributed systems. We describe the component model and show how to program and compose event-based distributed systems. We present the architectural patterns and abstractions that Kompics facilitates and we highlight a case study of a complex distributed middleware that we have built with Kompics. We show how our approach enables systematic development and evaluation of large-scale and dynamic distributed systems

Development of a Ligno-Cellulosic Polymeric and Reinforced Sheet Molding Compound (SMC)

The overall objective of this dissertation was to study the surface energy and acid-base characteristics of natural fibers, glass, a wood extract, and a sheet molding compound prepreg to facilitate the fabrication of totally synthetic and partially renewable sheet molding compounds (SMCs). The water absorption and micro-mechanical performance of the totally synthetic and partially renewable SMC composites were compared through accelerated aging experiments. Reinforcing glass sized for polyester, bast kenaf fibers, hot water extract from Acer rubrum, and a dicyclopentadiene modified polyester prepreg were analyzed by inverse gas chromatography to evaluate and help predict how the various components may interact in a crosslinked composite SMC. Dynamic Mechanical Thermal Analysis (DMTA) was used to determine how the components in the SMC changed as a function of hygrothermal aging by analyzing the glass transitions of the individual components in the SMC. Inverse gas chromatography (IGC) results indicated that the polyester prepreg material had an experimental dispersive surface energy value of 47 mJ/m2 that compared well with a rule of mixture analysis of the components in the SMC giving a value of 50 mJ/m2 both at 30?C. IGC results also indicated that the kenaf-prepreg material has a higher acid base interaction then the glass-prepreg material. The IGC results indicated that surface sizing of the kenaf fibers with styrene-maleic anhydride might improve the cohesiveness of the final kenaf based SMC. IGC results also indicated that hot water extract from Acer rubrum had a dispersive energy close to polystyrene and should be miscible in the prepreg material. Hygrothermal aging was done by soaking SMC samples at 70?C for 3, 168, and 1032 hour time intervals. Standard SMC fabricated with glass reinforcement had water uptakes of less than 5 weight percent after 1032 hours. SMC fabricated with kenaf had water uptakes at 1032 hours approaching 20 weight percent indicating the kenaf based SMC is not suitable for exterior applications or applications where water contact occurs. SMC fabricated with hot water extract from Acer rubrum had water uptake similar to, and in some cases, better then the standard SMC references. DMTA results indicated that thickening reactions took place without thickening agents in the SMC in the presence of excess absorbed water. The temperature range of –50?C to 260?C during DMTA testing effectively destroyed the kenaf based SMC. The glass based synthetic SMC was the most resilient to the heat ramps followed by the extract based SMC. Inverse gas chromatography is a useful tool for analyzing the dispersive and acid-base properties of components of a composite. Kenaf based and extract based SMC’s can be fabricated and the extract based SMC’s compare well with standard synthetic SMC’s for water absorption and micro-mechanical properties

Hemp Stem Epidermis and Cuticle: From Waste to Starter in Bio-Based Material Development

Nowadays, hemp farmers are facing an urgent problem related to plant stem disposal after seed harvesting. In this work, the commonly discarded epidermis and cuticle of hemp stems were valorized, turning them towards a sustainable recycling and reuse, contributing to the circular economy concept. Cellulose deprived of amorphous regions was obtained by a green process consisting of an ethanolic ultrasound-assisted maceration followed by mild bleaching/hydrolysis. The obtained hemp cellulose was esterified with citric acid resulting in a 1.2-fold higher crystallinity index and 34 ∘C lower Tg value compared to the non-functionalized hemp cellulose. Green innovative biocomposite films were developed by embedding the modified cellulose into PLA by means of an extrusion process. The structural and morphological characterization of the obtained biocomposites highlighted the functionalization and further embedment of cellulose into the PLA matrix. Attenuated Total Reflectance–Fourier Transform Infrared spectroscopy (ATR-FTIR) results suggested physical and chemical interactions between PLA and the organic filler in the biofilms, observing a homogeneous composition by Field Emission-Scanning Electron Microscopy (FESEM). Moreover, some increase in thermal stability was found for biocomposites added with 5%wt of the hemp cellulose filler. The obtained results highlighted the feasible recovery of cellulose from hemp stem parts of disposal concern, adding value to this agro-waste, and its potential application for the development of novel biocomposite films to be used in different applications

Growth, productivity, and utilization of kenaf (Hibiscus cannabinus L.): A promising fiber and fuel crop for Iowa

Producing natural fibers to replace finite synthetic fibers is a good strategy to move from a petroleum-based society to a bioeconomy. Kenaf (Hibiscus cannabinus L.) has been identified as a promising multi-purpose crop that could have potential to grow in the Midwest. It is critical to determine the varieties and management practices that are optimal to produce high quantity and quality of kenaf fibers in Iowa, where corn and soybean are prevalent. Information regarding its potential for biofuel is scarce and requires to be investigated. Finally, consequences of including kenaf in traditional cropping systems on soil quality need to be studied in this area of the U.S. In the first study (Chapter 2), we demonstrated that ‘Tainung 2’ and ‘Whitten’ were the most promising in Iowa. Also, when its biomass was pyrolyzed, kenaf could have potential in the production of levoglucosan that can be further upgraded into ethanol. Our second study (Chapter 3) showed that it exists an optimal combination of management practices that influenced kenaf productivity and morphology. In the third study (Chapter 4), we found that N fertilization does not have any influence on kenaf stem production. However, N and other agricultural practices did influence morphology and composition. Our fourth study (Chapter 5) investigated kenaf productivity in Iowa and Kentucky. The results showed that Kentucky has more potential than Iowa, but that kenaf production in Iowa was less variable than in Kentucky. Finally, in our fifth study (Chapter 6), we developed a model in APSIM for kenaf, which was used to analyze the effects of kenaf inclusion in corn-soybean systems on soil quality. Overall, this work showed that kenaf could be a promising alternative crop in Iowa

Modelling the Environmental and Economic Life Cycle Performance of Maximizing Asphalt Recycling on Road Pavement Surfaces in Europe

The road pavement industry, worldwide, has often shown reluctance in quickly implementing innovative practices; however, in the case of raw material consumption, a cultural change is necessary and, in this sense, sustainability assessment could play a major role. Along these lines, this research study aims to provide evidence to all the involved stakeholders (material producers, pavement contractors, and road authorities) of how life cycle-based techniques can be crucial in evaluating whether the adoption of asphalt mixtures with high contents of reclaimed asphalt (RA) for wearing courses is actually a sustainable practice for major European roads. An evaluation framework composed of a life cycle assessment, to calculate the carbon footprint of both pavement materials and pavement activities, and a life cycle cost assessment, performed to determine the overall economic burden of the related road pavement surface courses and maintenance strategies over a sixty-year analysis period, is presented and applied to selected case studies. These were developed together with three major European national road authorities and include scenarios involving the construction of road surfaces with asphalt mixtures containing up to 90% RA. Results have shown that whenever high-content RA mixes do not under-perform against conventional mixtures, up to 50% CO2eq savings can be registered and up to 60% economic cost reductions can be reported. The durability of road pavement layers remains a key parameter for any road pavement sustainability assessment exercises; therefore, in order to adapt the obtained results to other contexts, researchers should always consider conducting a sensitivity analysis of the reference service life and/or road authorities should somehow request road pavement durability as a pre-requisite within procurement practices

A STUDY OF SURFACE MODIFICATION EFFECT OF HEMP FIBERS ON THE BULK PROPERTIES OF HEMP-POLY (LACTIC ACID) COMPOSITES: THERMAL STABILITY, MECHANICAL, THERMO-MECHANICAL AND BIODEGRADABILITY

Biocomposites made with, natural fiber and bio-based polymers, have many advantages over their synthetic counterparts including low cost, low density, high strength and biodegradability. However, some biocomposites can present problems due to high moisture absorption, low thermal stability during processing, and poor adhesion between the fiber and polymer matrix. Recent studies have shown that surface modification of the fiber can improve its adhesion to the polymer matrix and enhance the bulk material properties. Nevertheless, the mechanisms by which such surface modifications exert their effects on bulk material properties have not been systematically studied. Therefore, the main goal of this study is to investigate the impact of surface modifications of hemp on the thermal stability, mechanical, thermo-mechanical, and biodegradability of biocomposites comprised of hemp and poly (lactic acid) (PLA). This pairing was selected because it offers superior mechanical properties. The three surface treatments tested were: alkali (mechanical interlocking), silane (coupling) and acetic anhydride (grafting). The latter was most effective at improving thermal stability, mechanical, and thermo-mechanical properties of hemp-PLA biocomposites, and all treatments improved these properties relative to untreated hemp-PLA controls. The thermal stability of the composites increased with an increase in fiber content up to 30% by fiber volume fraction for both silane and acetic anhydride modified hemp. However, thermal stability decreased with fiber content for alkali and untreated composites due to hydrogen bonding and inferior fiber-matrix adhesion, respectively. The activation energy of thermal degradation was assessed by applying Flynn-Wall-Osawa kinetic modeling to understand the fiber-matrix interface. The model predictions were consistent with experimental results and suggested that the mechanism by which, acetic anhydride treatment yielded superior thermal properties was related to high energy bond formation (C=O) between the fiber and polymer matrix. When tensile and flexural properties of composites were assessed, 30% fiber volume fraction was optimal, and this ratio also improved stiffness and damping properties of the composites during thermo-mechanical study. A biodegradability study of the treated and untreated hemp-PLA biocomposites was undertaken. ASTM standard 5511-11 was modified to stimulate landfill disposal conditions. Degradation of all treatments as well as untreated biocomposites was negligible over 50 d, although visual inspection of SEM images showed greater evidence of cracking in the composite samples than in pure PLA controls. From this study it can be concluded that higher bond energy at the fiber-matrix interface due to surface modification of natural fiber results in higher activation energy of thermal degradation resulting in enhanced bulk material properties of the biocomposites

Intelligent redundant actuation system requirements and preliminary system design

Several redundant actuation system configurations were designed and demonstrated to satisfy the stringent operational requirements of advanced flight control systems. However, this has been accomplished largely through brute force hardware redundancy, resulting in significantly increased computational requirements on the flight control computers which perform the failure analysis and reconfiguration management. Modern technology now provides powerful, low-cost microprocessors which are effective in performing failure isolation and configuration management at the local actuator level. One such concept, called an Intelligent Redundant Actuation System (IRAS), significantly reduces the flight control computer requirements and performs the local tasks more comprehensively than previously feasible. The requirements and preliminary design of an experimental laboratory system capable of demonstrating the concept and sufficiently flexible to explore a variety of configurations are discussed

Extraction and characterization of Retama monosperma fibers

The aims of this study were to determine the good conditions for fibers extraction from Retama monosperma leaves and their mechanical, physical and chemical characteristics. The fibers were extracted using a range of NaOH concentration from 1 to 16% in a period of treatment of 1 to 24 h, coupled with a physical treatment. For the evaluation of physico-mechanical characteristics, 200 samples were performed in the tensile test. The biochemical composition of the fibers was determined after separation of the parietal compounds. The results show that the best fiber yield was 11.51% obtained by a treatment of 14% NaOH for 8 h, followed by a physical treatment. The fibers biocomposition was 87.3% of cellulose, 7.5% of hemicelluloses and 1% of lignin. The Young's modulus was 13.3 GPa, tensile strength was 110 MPa and density was 1.3 g/cm3. The average fiber length was 155.7 mm. The fibers yield and characteristics showed that R. monosperma plant may in future be suitable source for natural fibers.Key words: Retama monosperma young stems, fibers, extraction, characterization